On its first move, the pawn can either move one space or two spaces forward.
A pawn captures diagonally, which is kind of tricky.
But another way the pawn can capture is called en passant. This only happens when on its first move, an opponent's pawn moves two spaces forward and ends up on the same rank as one of your pawns, you can capture it. There is a rule though: You have to take the pawn on the move exactly after it moves two spaces forward. You can't take it too late! Here's an example: