There was a celebration going on in the city called The Passover. It helped the people remember when God rescued them out of Egypt; remember the story of Moses?!
This time though, Jesus wanted them (and us) to remember how He was about to rescue from sin!
“While they were eating, Jesus took some bread, and after a blessing, He broke it and gave it to the disciples, and said, “Take, eat; this is My body.” 27 And when He had taken a cup and given thanks, He gave it to them, saying, “Drink from it, all of you; 28 for this is My blood of the covenant, which is poured out for many for forgiveness of sins.”