Agonizando means "agonizing" or "in agony". It's a highly dramatic word that paints a vivid picture of intense suffering.
In the song, Luis Fonsi sings, "Estoy muriendo, muriendo por verte, agonizando" (I'm dying, dying to see you, agonizing). He uses this powerful verb to describe the extreme emotional pain of being separated from the one he loves. It elevates the feeling beyond simple sadness to a state of desperate, soul-crushing torment, making it a truly unforgettable word for expressing heartbreak.
Ever made a call you knew you shouldn't? That's the whole mood of "Vacío". Luis Fonsi kicks it off by admitting he's breaking a promise, saying, "Perdona si te estoy llamado en este momento" (Sorry if I'm calling you right now). He knows it's the wrong time and that she's with someone else, but he just can't help it after a few drinks. He feels like he's going crazy and literally dying to see her again: "Estoy muriendo / Muriendo por verte" (I'm dying / Dying to see you). The whole song revolves around this feeling of emptiness, or "vacío", that he says only she could fill.
Then Rauw Alejandro comes in with his side of the story, and he's just as stuck. He's so sure she hasn't moved on either, telling her that when her new guy kisses her, "Solo los míos estás sintiendo" (You're only feeling my kisses). It's a bold claim! Both of them confess that even though they're with new people now, they're still completely fixated on the past. The song's big question is right there in the chorus: "¿Cómo se llena, baby, este vacío si tú no estás conmigo?" (How do I fill, baby, this emptiness if you're not with me?).