Wikipedia
Player-coach
A player-coach (also playing coach, captain-coach, or player-manager) is a member of a sports team who simultaneously holds both playing and coaching duties. A player-coach may be a head coach or an assistant coach. They may make changes to the squad and also play on the team.
Very few current major professional sports teams have head coaches who are also players, though it is extremely common for senior players to take a role in managing more junior athletes. Historically, when professional sports had much less money to pay players and coaches or managers, it was much more common to find them. Likewise, where player-coaches exist today, they are more common at the lower levels where money is less available, but not exclusively.