When someone throws a Queen, they reverse the direction of play.
Like in life, so in card games, dames turn things around. The game starts in counter-clockwise direction by default. When a Queen is played, the current direction is reversed. This can happen any number of times during a game.
In Mau King, the direction of play is indicated by an arrow displayed on the table. When someone plays a Queen, this arrow is changed to show the new direction of play.
In two-players game the Queen has no effect, but the arrows on the table still show the theoretical current direction of play.