White to move. Find the one move that wins. About 700 ELO.
One rook move ends the game.
Look at the open e-file.
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.
Rooks love open files. When an enemy king hides behind pawns, check its back rank first.
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.