This exercise is from 2 v 1 Attacking Drills and Exercises
The supporting attacker, labeled B, is up field from the attacker, labeled A. Attacker A is committing defender C with the dribble numbered 1. Attacker A then passes the ball to attacker B with the pass numbered 2. This pass is back up field from the direction that the attacker wants to go. Usually this means that the supporting attacker, labeled B, is closer to their own goal than the teammate who is committing the defender with the dribble. The solution is a High Wall Pass which will have its' first pass back up field and then splits the defenders with a straight pass down field
In Square A1 the attacker, labeled A, dribbles to commit the defender. The dribble is numbered 1. In Square A1 the pass is hit backwards, numbered 2, to the supporting attacker. The pass should be to the foot furthest away from the defender nearest the supporting attacker. Attacker A then makes a hard diagonal run in behind the defender labeled C with a run numbered 3.
In Square A2 the supporting attacker splits the defenders with the straight return pass. This leaves attacker A with the ball behind the defense with the hoped for results.
