“POV” (which stands for “point-of-view”) is a shot that simulates what a character is seeing. Typically, a POV shot is part of a two or three shot sequence. First, we see the actor looking at something. Then we see what he is looking at... then we see the actor again.
In the example at the right, Cary Grant is on the top of a building—his nemesis has just rolled down the steeply pitched roof. Grant looks to see where the bad guy ended up, and the shot changes so viewers can see what he sees. In the third shot we return to Grant.