Answer: Él
Explanation:
The subject in this sentence is "A male player". To replace this subject, we have to use the third-person subject pronoun, masculine in the singular "Él".
Él juega en un equipo.
He plays on a team.
This Spanish pronoun has a written accent to differentiate it from the masculine, definite, article "El", which has no written accent.
El jugador.
The player.