One defending player is trying to catch the player in possession of the ball.
Players in possession of the ball can not move. Players without the ball can move though to make themselves available to receive the pass.
If a player is caught whilst in possession of the ball they must now become the catcher and the drill starts again.
Rebounding is the least glamorous thing in basketball and one of the most decisive. It is also almost entirely a habit, which means it is entirely coachable.
Good spacing is only the start. The best modern offences teach players to attack the defence's rotations and play in a permanent 4-on-3 - here is how to coach that read.
The ball screen produces almost half of all professional offensive possessions, yet most teams still teach it as a memorised play. The modern approach trains the read - giving players a framework to decide based on what the defence does, not what the coach called.