What Passovers took place in the bible and should we observe it today?

Passover began when God sent the final plague upon Egypt, i.e. the death of every firstborn male. To spare the Israelites, God instructed them to sacrifice a spotless lamb, apply its blood on the doorposts, and stay inside. When the Lord saw the blood, He would “pass over” that house, sparing those inside from judgment. This marked the beginning of Israel’s freedom from Pharaoh and slavery.

EX. 12:12 ‘For I will pass through the land of Egypt on that night, and will strike all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am the Lord.
EX. 12:13 Now the blood shall be a sign for you on the houses where you are. And when I see the blood, I will pass over you; and the plague shall not be on you to destroy you when I strike the land of Egypt.

Furthermore, God commanded the Israelites to observe Passover every year as a memorial of His faithfulness:

EX. 12:14 ‘So this day shall be to you a memorial; and you shall keep it as a feast to the Lord throughout your generations. You shall keep it as a feast by an everlasting ordinance.

In the man Jesus Christ we find complete fulfillment of Passover, whom the New Testament calls our Passover Lamb:

1COR. 5:7 Therefore purge out the old leaven, that you may be a new lump, since you truly are unleavened. For indeed Christ, our Passover, was sacrificed for us.

Just as the lamb’s blood spared Israel from death, Jesus’ blood spares believers from the wrath of God. His crucifixion occurred during Passover, linking His sacrifice directly to the original event:

JOHN 19:14 Now it was the Preparation Day of the Passover, and about the sixth hour. And he said to the Jews, “Behold your King!”

Passover was to be celebrated on the 14th day of the first month (Nisan), with a meal that included unleavened bread, bitter herbs, and a lamb, each element symbolizing aspects of the Exodus.

Passover was not a command given to the Gentiles, and therefore, we are not obligated to observe the ongoing Passover Seder meal, traditionally held in April. Instead, the Law, including Passover, was given specifically to the Israelites as a unified covenant composed of 613 commandments, and Scripture consistently presents the Law as a complete, indivisible whole. Perhaps the clearest explanation of this principle comes from Dr. Arnold Fruchtenbaum of Ariel Ministries when he teaches:

It is the principle of the unity of the Law of Moses that lies behind the statement found in James 2:10: “For whosoever shall keep the whole law; and yet stumble in one point, he is become guilty of all.” The point is clear: a person needs only to break one of the 613 commandments to be guilty of breaking all of the Law of Moses. This can only be true if the Mosaic Law is a unit...To bring the point closer to home, if a person eats ham, according to the Law of Moses he is guilty of breaking the Ten Commandments, although none of them says anything about eating ham.”  Excerpt from MBS006

A Christian can’t pick a few elements from the Law (e.g., the Ten Commandments) and place them in a special category apart from the rest of the Mosaic Law, especially if our purpose in doing so is an attempt to preserve them alongside the Law of Christ. Rather, the Mosaic Law is an all or nothing proposition: either a man lives under the Law of Moses and keeps all 613 laws, or he lives by faith and dispenses with the Mosaic Law entirely in favor of the newer, better law of Christ.

Today, a Christian's passover is found in Jesus Christ and are free from the Law. Jesus is both our justification and our sanctification. Thankfully God provided a better way to pleasing him: faith in Christ and reliance on the Holy Spirit means through faith in Him we have established or upheld the Law seen in Romans 3:

ROM. 3:1 Do we then make void the law through faith? Certainly not! On the contrary, we establish the law.

The principle reason that the New Covenant is called “good news” is because of how it addresses all the weaknesses and deficiencies of the Old Covenant, namely the Feasts and Holy Days. Among its many improvements, the New Covenant we have in Christ provides a means of living a holy life, where before the Law was powerless to accomplish the same as seen in Hebrews 7:

HEB. 7:17 For He testifies:
“You are a priest forever
According to the order of Melchizedek.”
HEB. 7:18 For on the one hand there is an annulling of the former commandment because of its weakness and unprofitableness,
HEB. 7:19 for the law made nothing perfect; on the other hand, there is the bringing in of a better hope, through which we draw near to God.

Rather than attempting to keep a set of laws, Holy days or commands written on stone, which neither adjust nor grow to address our changing circumstances, Christians are to be guided by the Spirit indwelling us:

GAL. 5:13 For you, brethren, have been called to liberty; only do not use liberty as an opportunity for the flesh, but through love serve one another.
GAL. 5:14 For all the law is fulfilled in one word, even in this: “You shall love your neighbor as yourself.”
GAL. 5:15 But if you bite and devour one another, beware lest you be consumed by one another!
GAL. 5:16 I say then: Walk in the Spirit, and you shall not fulfill the lust of the flesh.
GAL. 5:17 For the flesh lusts against the Spirit, and the Spirit against the flesh; and these are contrary to one another, so that you do not do the things that you wish.
GAL. 5:18 But if you are led by the Spirit, you are not under the law.

In submitting to the Spirit, we are living according to the Law of Christ. Walking according to the Spirit is now the law guiding all believers, and it’s the only law we need. 

On the other hand, a Christian is free to observe the Passover, as long as their personal conviction doesn't get put on those around them. In other words, observing the Passover doesn't make a "better Christian."

You may find the following articles on our website helpful in addressing your question:

How many passovers were there the week Jesus died?

Three Separate Passovers Recorded in John

Is a Christian Under the Law of Moses

Scripture quotations taken from the (NASB®) New American Standard Bible®, Copyright © 1995, 2020 by The Lockman Foundation. Used by permission. All rights reserved. www.lockman.org