Most Helpful Guy
it means a lot of things.
if he does that, then he's a confident guy.
placing hands on a women's lower back arouses her and makes her more sexually active.
Also, it may mean that he wishes to get closer to you and that he is interested in you and that he's got your back no matter what3
Most Helpful Girl
he's trying to make a move some of its polite and friendly but its totally a flirting move he really wants to touch your ass but he's being polite3