White to move. Find the one move that wins. About 700 ELO.
Black's king is boxed in by its own pawns. Mate in one.
Which rank can't the king escape from?
A move that attacks the king with no way out: the game ends on the spot.
Look at every check first. Count the king's escape squares and ask which check covers all of them.
A king behind three unmoved pawns has no air. Give yours a 'luft' square (h3 or g3) before it's too late.
Solve it on the board above, or take a hint. Every ChessLvl puzzle is checked by a chess engine to have exactly one best move.