Pourquoi c’est nulle alors qu’il ne reste que le roi à mon adversaire et moi plein de pièces pour le mettre en échec . C’est vraiment frustrant
It's because you ran out of time and can't win and your opponent doesn't have sufficient material to mate you, so they can't win. So it's a draw.
https://support.chess.com/article/268-my-opponent-ran-out-of-time-why-was-it-a-draw
Or, you stalemated your opponent, which means it's their move, they're not in check, and they have no legal moves.
https://support.chess.com/article/682-what-is-stalemate
Pourquoi c’est nulle alors qu’il ne reste que le roi à mon adversaire et moi plein de pièces pour le mettre en échec . C’est vraiment frustrant