Passover is a celebration of leaving Egypt, slavery, and pharaoh
The Jewish people leaving didn't have time to let the bread rise. To this day that is represented when on Passover you don't eat anything that rose while being made or anything with yeast.
The first two nights of Passover are Seders outside of Israel, but in Israel there is only one. Seders are dinners with family, and you recite prayers you normally wouldn't.
During the Seder you have a plate with a egg, horseradish, parsley, bitter herbs where you dip into saltwater to represent the bitterness and tears shed while leaving their homes, a bone, and haroseth which later in the Seder is the second thing you eat.
A part of the Seder is a prayer about the ten plagues for each plague you spill a drop of wine or grape juice on your plate. The ten plagues were, Water turned to blood, frogs, lice, flies, diseased livestock, boils, hail, locusts, darkness, and death of the first born son.
The youngest child also asks the four questions these questions are, Ma nishtanah halailah hazeh mikol haleilot? Sheb’khol haleilot anu okhlin hametz umatzah; halailah hazeh, kuloh matzah. Sheb’khol haleilot anu okhlin sh’ar y’rakot; halailah hazeh, maror. Sheb’khol haleilot ein anu matbilin afilu pa’am ehat; halailah hazeh, shtei f’amim. Sheb’khol haleilot anu okhlin bein yoshvin uvein m’subin; halailah hazeh, kulanu m’subin. These point out the differences in what we eat and how we sit.