"Recitation" = recite
Basically, recitation classes are for courses with a large class size or complicated material (like math or science). Usually these classes will have 1 professor and several student teachers. The professor will teach the large class (also called the Lecture) and cover new material. The student teachers will teach the recitation classes and go over the week's material in more detail. Because there is often a lot of material to cover in the large class, there isn't a lot of time to go over specifics or answer questions. The recitation class gives you the opportunity to address any questions or issues in a smaller classroom environment. Also, quizzes and homework are frequently given &/or collected during the recitation class.
I went to a large university (Rutgers) and graduated in 2003.