Prophylaxis
Prophylaxis is a move that stops the opponent’s idea before it happens, rather than chasing a threat of your own.
The move can look slow: h3, a3, Kh1, or a rook to a better file. Its value is that the opponent’s plan — a pin, a break, a piece landing on a hole — never gets started.
h3 keeps a bishop off g4, so the knight on f3 cannot be pinned to the queen. Nothing is hanging, and no capture is forced. The point is that …Bg4 stops being a problem.
Good prophylaxis answers a real idea, not a ghost. If the opponent had no useful pin or break, the same pawn move is only a weakness. The coach names it when the prevented plan was actually on the board.