Palm Sunday is the celebration of the triumphant entrance of Christ into the royal city of Jerusalem. He rode on a colt for which He Himself had sent, and He permitted the people to hail Him publicly as a king. A large crowd met Him in a manner befitting royalty, waving palm branches and placing their garments in His path. They greeted Him with these words: “Hosanna! Blessed is he who comes in the name of the Lord, even the King of Israel! (John 12:13).

https://oca.org/saints/lives/2018/04/01/20-entry-of-our-lord-into-jerusalem-palm-sunday