What is Baytzah?

Answer 1

Baytzah is hard-boiled egg.

Baytzah is symbolic of the regular festival sacrifice brought in the days of the Temple. Some authorities have interpreted this as a symbol of mourning for the loss of the two Temples (the first was destroyed by the Babylonians in 586 B.C.E., the second by the Romans in 70 C.E.). With the Temples destroyed, sacrifices could no longer be offered. The egg symbolized this loss and traditionally became the food of mourners.