The picture above shows a training drill involving two teams i.e. Team Red and Blue. With two players in Yellow at the right and left flank.
The drill starts when the players of Team Blue play some passes between themselves before playing a through ball to the Yellow player at the left flank. The Yellow player after receiving the ball, plays it into the penalty box where the players of Blue team rush into the box to receive the ball and score the goal while the Red players also rush into the box in order to intercept the ball and stop the Blue team to score the goal.
This is good training drill for both the sides. It helps the players to practice the technique of keeping the possession and playing long balls and crosses. It also helps the players on the defending side to experience and figure out the required tactics to stop such attacks in real match scenarios.