Easter celebrates Jesus' resurrection. His cruel death by crucifixion took place at the same time as the Jewish holy celebration of Passover. What they had been symbolizing for over 1000 year with the killing of sacrificial lambs and the passover supper was now happening to the lamb of God.
On that very day and at that very hour when people throughout the land were selecting and slaughtering passover lambs, Jesus was crucified.
The way Jesus died also fulfilled many other Old Testament prophecies in amazing detail.