Desvelado literally means "without sleep" and describes the state of being up all night. It's a more poetic way to say you're sleepless, often because you're consumed by powerful emotions like love, worry, or inspiration.
In the song, the singer is desvelado because he wanders the streets all night, obsessively searching for a mysterious woman whose voice he heard on the radio. This single word perfectly captures the romantic longing and restlessness at the very heart of the lyrics.
Ever fall in love with someone you have never actually seen? In "Desvelado", fronted by California's Fuerza Regida, the singer is utterly obsessed with a voice he heard through his speakers. He admits right off the bat, "Con ella me enamoré / Que nunca la conocí" [I fell in love with her, though I never met her]. Now he is trapped in a loop. He glues himself to the radio every single day ("Escucho cada día la radio / Seguro que la vuelvo a oír" [I listen to the radio every day, sure I will hear her again]), convinced this mystery speaker is his destiny.
The word desvelado means sleep-deprived or kept awake, and he means it literally. He is wandering the streets at night asking "¿Dónde andará?" [Where could she be?], waking up in tears because his longing will not let him rest. Between the desperate romantic lines, Fuerza Regida throws in street-level Mexican-American slang that breaks the melancholy mood. Shouts like "¡Otro pedo!" [literally "another fart", meaning something is on a whole different level of greatness] and "A huevo, mija" [Hell yeah, baby] bring a gritty energy to a classic love-struck serenade about staying up all night searching for an invisible angel.