The picture above is of a training drill being performed in a rectangular block made on the field. It involves players in Red , Yellow and Green kits. The players in Green act as defenders.
The drill starts when the Red player on the left side of the picture plays a pass to the Red player in the block region. The Red player after receiving the ball plays it to the Yellow player at the left bottom of the picture. The Yellow player then plays it back to another Red player on the Right side of the region. The Red player plays it to the Yellow player on the top side of the picture, who plays it to the Red Player on the right side of the marked region. The Players in Green, whereas, keep trying to intercept the passes being played between them.
This helps the players improve their passing in pressure situations and keep the possession of the ball.