Chaleco antibalas is a striking phrase that literally translates to "bulletproof vest". It's a perfect example of a modern, creative metaphor in music.
In this song, the singer says he used to have a chaleco antibalas for his heart, meaning he was guarded and afraid of getting hurt. But with his new love, he doesn't need it anymore, beautifully illustrating how trust and true love can break down emotional walls.
This song is a massive, over-the-top declaration of love, and it's fantastic. Grupo Frontera and bachata king Romeo Santos team up to describe a woman who is so perfect, she must be an angel who fell from heaven. The singer was in a bad place before she arrived, saying she came in his worst moment and "reviviste lo que estaba muerto" [revived what was dead]. He even had a "chaleco antibalas" [bulletproof vest] for his heart, but with her, he doesn't need it anymore.
He piles on the compliments, comparing her to a work of art and his favorite song. In a great little nod to Romeo Santos's past, he calls her "La bachata preferida, Aventura, mi obsesión" [My favorite bachata, Aventura, my obsession], referencing Santos's famous former band. The central idea is that she's so perfect, they have to ask God "Si se le cayó un ángel de arriba" [If an angel fell from above], because she has the face of one and is only missing her wings.