The King is reinforcing the Horse-carriage.

The Horse at B61 renders the Black Cannon a ‘paralysed’ carriage.

Chinese xiangqi books usually call the ending a ‘Returning the Buddha to his temple’ checkmate (送佛归殿), or a ‘3-pace Pawn Charge’ checkmate (三进兵杀法). Either name vividly describes the attacking process, but it is a Smothered Mate that ends the game.

Red applies the ‘Piercing the heart’ tactic with R7=5, to create the position for Smothered Mate.