Jaque mate is the Spanish term for "checkmate," the game-ending move in chess where the king is trapped and cannot escape capture.
KAROL G uses this as a powerful metaphor for the end of a relationship. When she sings, "Te pusiste en jaque mate" (You put yourself in checkmate), she's telling her ex that he made a final, losing move and there's no way for him to win her back. It's a clever and dramatic way to declare a definitive victory.
This song is a fantastic breakup anthem! KAROL G is talking to an ex who cheated on her. He's telling everyone he's over her, but she knows the truth. She sings, "Dices que de mí ya te olvidaste... Cuando yo te hacía pom-pom-pom" (You say you've already forgotten me... when I used to make you go pom-pom-pom). She's calling him out, saying he only thinks she's sitting at home sad about him.
But she's doing the opposite! The whole point of the song is in the chorus: "Mi cama suena y suena" (My bed is creaking and creaking). She's not just moving on, she's having a great time with new people. She tells him his chance is gone with some great lines like "En mi cerradura ya no entra tu llave" (Your key doesn't fit in my lock anymore) and "No te preocupes, tu tren ya pasó" (Don't worry, your train has already left). She even says his cheating backfired: "La matemática a ti te falló" (Your math failed you). It's a powerful and funny track about taking back control after a bad relationship.