Anastasia's Mate is a knight-and-rook pattern that punishes a king caught on the edge of the board: the knight covers the king's two diagonal escape squares from one side, and the rook slams down the open edge file for mate. It's named after a 1803 novel that featured the position, one of the oldest named mates in chess.
The shape to recognize: enemy king on the h-file (or a-file), your knight on e7 (or the mirror squares) covering g8 and g6, and an open path for a rook to reach the h-file. In real games it often starts with a queen sacrifice on h7 to drag the king out; here the king is already caught.
The knight on e7 covers both g8 and g6. Black's king is stuck on the h-file with its own pawn behind it.
The knight has the escape squares covered. Finish it.