Tornillo literally means "screw". It's a fantastic word to learn from this song because it's used in a very common Spanish idiom and is also the artist's name!
In the song, he sings, "Me hace falta un tornillo", a playful expression that literally means "I'm missing a screw". It's the Spanish equivalent of saying "I have a screw loose" or "I'm a little crazy", and he uses it to proudly embrace his wild side. It's an especially clever line, as it's a nod to his own stage name, Tornillo.
Mexican rapper Tornillo gives us a classic story of neighborhood love and obsession in "Morena." He's completely captivated by a woman he saw dancing cumbia, describing her with an almost dangerous intensity: "Pelo largo, boca que quema / Labios rojos que me envenenan" (Long hair, a mouth that burns / Red lips that poison me). He only met her once in the barrio, but he can't stop thinking about her and is desperate to find her again, holding onto the hope that they'll reconnect.
But this isn't just a simple crush. There are rumors on the street that she's a "criminal" and so desired that everyone wants her. Tornillo doesn't care what people say, insisting, "Yo digo que tú eres buena, otros dicen que yo estoy mal" (I say you're good, others say I'm wrong). He connects his own reputation as a kid from the streets who smokes weed with her mysterious nature, seeing them as two of a kind. He admits he's missing a screw—a nod to his name, Tornillo—and that he's never going to change who he is.