Idk what to do...

So im 18 and i work on cars at a shop with 3 guys total including the manager.... But my manager has said some pretty sexual things towards me and he has also grabbed my waist quite a few times and has touched my butt and hes 40!... And i wanna get ahold of hr but in too scared and i know u will freeze up and not say the right thing like im scared to even be the last one working if the other guys get to go home early...my family doesnt even know what is going on because im afraid to tell them...

Idk what to do please let me know if you have any advice...