Palm Sunday is the first day of Holy Week, leading up to the Jewish holiday of Passover. Jesus rode into Jerusalem on the back of a donkey. The Jewish people, His chosen people, celebrated his arrival just days before they traded Him in for a murderer and called for His crucifixion. They saw Him, for a short time, as their Savior. The one that would give them the freedom from Roman control they had been longing for.
As Jesus was entering the town on the donkey, with her colt in tow, the people laid out their cloaks or palm branches on the ground before His path. Why palm branches? There were an abundance of palm branches in that area but they also had a special meaning. Palm branches were a symbol of victory. Laying them at his feet showed submission to His power to, in their hopes, overthrow the Roman rule. What they didn’t understand was that He did not come to get victory over the Romans but over sin and death itself. He came to be the sacrificial Passover lamb. The people would no longer need to make atonement, by sacrificing an animal, to cover their sins.
This is generally celebrated by reading the story of Jesus triumphal entry into Jerusalem which is found in all of the New Testament Gospels (Matthew, Mark, Luke, & John). Some churches will display palm branches, others burn them and apply the ashes to the foreheads of those that believe. Others sing songs of praise with the same word that was spoken by the Jewish people on that day, “Hosanna” which means “Please, Lord, save us.”
For some of us, we also use this day to look forward. We look to the day when Jesus will again return for His people, all those who believe that He conquered sin and death. He will again have victory over evil and win the final battle. This prophesy, story of the future, is found in Revelations 7:9-17. Considering current events, there are many who believe that day is coming very soon.
Sources: https://www.biblestudytools.com/bible-study/topical-studies/what-is-the-meaning-of-palm-sunday-and-why-celebrate-it.html; https://www.biblestudytools.com/bible-study/topical-studies/what-does-hosanna-mean.html; https://www.bible.com