Madrugá is a colloquial and shortened form of "madrugada," which means "dawn" or "early morning." It's a beautiful and evocative word that paints a picture of the quiet, mystical hours before sunrise.
In the song, the lyrics mention "Luna de la madrugá" (Moon of the dawn), personifying the moon as a silent witness to a secret love. This poetic usage makes the word feel intimate and adds a touch of romantic mystery to the song's narrative.
La-33's "Dime por Qué Será" is a beautiful, romantic salsa tune that captures the feeling of being completely smitten. The singer is utterly captivated by someone, to the point of sleepless nights. He asks the "luna de la madrugá" [moon of the early morning] if it remembers seeing her smile, and how the breeze caressed her hair. He's mesmerized by her eyes, which he says are like a "lucero de mil colores" [star of a thousand colors], and her mouth, which seems to protect him from all harm.
He's so taken with her that he just can't understand why he feels this way, repeatedly asking, "dime por qué será" [tell me why it will be]. He yearns to be close to her, to kiss her under the moonlight, and confesses, "muero por verla" [I die to see her]. It's a sweet, almost desperate plea to understand the magic of new love, all set to an irresistible salsa beat.