If by "presider" you mean "priest" (the person who preaches the religion at church) it just a place were they sit. Nothing special. It's a form of respect for catholics. Catholics respect the priest and believe them to be a sorta very special friend of god. Other catholics may call him "one of gods might servants." We don't refer to him usually as "presider" or "priest". We call hims "Father...." and then his last name.So again its just for respect of the priest. A big chair raised a bit above of pews.