getting eaten out

ok I'm a freshman and this guy is a junior he's kinda just a hook up but he wants to eat me out and I'm not sure how I feel about it I told him I was uncomfortable and he understood he didn't want to pressure me but I want to let him do it I'm just uncomfortable with it he's more experienced and he also wants to have sex which I'm fine with so idk what it is about getting eaten out?!?