What do each of the things on the Seder plate symbolize?
The hard boiled egg represents the festival sacrifice brought at the Holy Temple in Jerusalem on the afternoon before Passover (Pesach).
The roasted chicken neck represents the pascal sacrifice brought at the Holy Temple in Jerusalem on the afternoon before Passover (Pesach).
The horseradish and/or romaine lettuce stalks represent the bitter suffering of the Jews in Egypt.
The apple, pear, nut, and wine mixture resembles mortar, symbolic of the mortar used by the Israelites to make bricks while enslaved in Egypt.
The horseradish and/or romaine lettuce stalks are used as morrow in the "sandwich" later in the Seder.
Why do we drink four cups of wine?
Four expressions of "freedom" or "deliverance" are mentioned in the Torah in connection with our liberation with Egypt.
The Children of Israel, even while in Egyptian exile, had four great merits:
They did not change their Hebrew names.
They did not change their Hebrew language.
They remained highly moral.
They remained loyal to one another.
Wine is used because it is a symbol of joy and happiness.
Why do we eat Matzah?
We left Egypt in such haste that where was no time to wait for the dough to rise, and we ate matzah, unleavened bread.
With only this unleavened food, our ancestors faithfully relied on the Al - mighty to provide sustenance for our entire nation of men, women, and children.
Each year to remember this, we eat matzah the first two nights of Pesach and fulfill the commandment of "Matzahs shall you eat..." The Matzah itself symbolizes faith.
At the Passover Seder, there are three matzahs. The middle matzah is broken in half, and hidden.
The half which you hide for dessert, is called the Afikoman.
Most of the things at the Seder stand for both slavery and freedom.