In Hebrew, we call the Seder plate a “Ka’arah”. Before the Seder we arrange the Seder Plate by placing three whole Matzot in a cover. Then we arrange symbolic items on top:

Zeroah: A Roasted Bone - This reminds us of the Pesach offering we used to bring in the Holy Temple in Jerusalem.

Beitzah: A hard-boiled Egg - This reminds us of the festival offering which was brought to the Holy Temple on Pesach.

Maror: Horseradish Root - These bitter herbs symbolize the harsh suffering and bitter times we endured when we were slaves in Egypt.

Charoset: A mixture of chopped apple, walnuts and red wine - Ground up together, Charoset resembles bricks and mortar, reminding us how hard we were forced to work when we were slaves in Egypt.

Karpas: This is usually sprigs of parsley - We dip the Karpas into salt water at the beginning of the Seder, representing the salty tears we cried when we were slaves.

Chazeret: This is the second portion of bitter herbs which we eat during the Seder - This is eaten in a Matzah sandwich together with Maror.


haggadah Section: Introduction
Source: Chabad.org (edited)