The picture above is of a training drill called “Verticalizzazione o Profondita” in Italian which translates to “Verticalization or Depth” in English.
It involves two groups of four players each. One player from each group is waiting on a separate section of the area, while the other players of both the groups are in the center area.
The players of which group has the ball, passes it to his teammates and to the fourth teammate who is present at the separate sections. The players of the other team who are in the center area try to take the possession from the opposing team, remaining in the center area only. When the other team successfully intercept to get the ball, now its their turn to keep the possession by passing it between their players at the center area and on the separate section until they are intercept by the players if the other team.
This drill helps to understand the concept of playing the ball deep and keeping an order of passing the ball in order to keep the possession in a real match.