What does the name Keziah which means cassia in Hebrew really mean?

Keziah does not mean "cassia" in Hebrew. The name Keziah is a girls' name of Hebrew origin, meaning "cassia". Cassia is a genus of flowering plants in the family Fabaceae, native to tropical and subtropical regions of the world. The name is derived from the Hebrew word qetzi'ah, meaning "cinnamon tree", which is a type of cassia tree.