In this position, white checkmated black in 3 moves because of black's back rank weakness. If the h7 pawn was on the h6 square, then white wouldn't be able to checkmate black very easily, although white could still win because of the extra queen and the knight.
In this position, the knight on the e2 square is making sure that the king doesn't escape to the g1 square and g3 square. The black pawn in g2 is making sure that the king doesn't escape to the g2 square, and the rook is checking the king.
Now I will show you a game that involves the Anastasia's Mate