This is the 5892nd most frequent Portuguese word.
belga
Belgian.
In this sentence, 'belga' is used as an adjective to describe the nationality of the player, meaning 'Belgian'.
Ele é um jogador belga famoso.
He is a famous Belgian player.
Here, 'belga' again serves as an adjective specifying the origin of the chocolate, which comes from Belgium.
Eu experimentei um chocolate belga delicioso.
I tried a delicious Belgian chocolate.
In this usage, 'belga' is employed as a noun referring to a person from Belgium.