Player 1 Raises
Player 2 calls
Player 3 reraises
What player 3 is doing is the squeeze play.
Basically when someone opens, any number of players call in between, and we reraise, it's called a squeeze.
This can be compared to 3betting, which would be just reraising one opener (and no callers in between).
Basically the best spots to do this are when you think the initial raiser is opening a wide range of hands, the callers are flatting weaker ranges of hands (things like 76s, 55, JTo, etc), and they can all fold well to 3bets.
The big difference between squeezing and 3betting is the dead money. It gives us a better price on our bluff, so our bluff needs to work less often to be profitable.