Bellaca is a slang term, particularly common in some Latin American countries, that can mean "naughty" or "horny." It's a word with a strong, suggestive connotation.
In "Labios De Cereza," the lyric "Mami, tú te ves bellaca" (Mommy, you look bellaca) is used to describe the woman as looking very attractive and alluring in a sensual way. It's an interesting word choice because it's not a standard romantic term, making it stand out and adding a playful, provocative edge to the song.
T3R Elemento builds this whole song around one image: cherry-red lips. The hook says it outright, "Labios de cereza" [cherry lips], and he barely lets go of it, following straight up with "Unos ojos que me matan" [eyes that kill me]. He sounds a little stunned by his own luck too, in "A mi Dios y un tal destino" [to my God and a certain destiny], thanking whatever brought her to him.
That gratitude sits right next to real desire. "Mami, tú te ves bellaca" [babe, you look so turned on] drops into the middle of an otherwise gentle song, and a few lines later he is back to calling her his "regalo divino" [divine gift] and admitting "Que sienta maripositas" [that I feel butterflies], plain and almost childish, which is exactly why it lands.