Jangueaba' is a fantastic example of Spanglish, derived directly from the English phrase "to hang out". It's a popular slang term in many parts of Latin America, especially the Caribbean, that means exactly what it sounds like: to hang out, chill, or spend time with friends.
In the song, Quevedo sings nostalgically, "hace un año tú jangueaba' a mi lado" (a year ago you used to hang out by my side), remembering a past time with his ex. The word itself, jangueaba', is the past tense (jangueabas), showing a repeated action, but with the final 's' dropped, a common feature in this dialect. It's a perfect word to learn if you want to understand modern, everyday Spanish.
This song is all about being completely stuck on someone you know you shouldn't be. Quevedo is alone, scrolling through his phone, waiting for a message from a girl who is with someone else. He's literally just lying in bed, obsessing over her chat, as he says: "En tu chat metido, tumba'o en la cama / Esperando que me hables cuando Ă©l no te habla" (Stuck in your chat, lying in bed / Waiting for you to talk to me when he doesn't). It's that feeling of being someone's second choice, and he knows it.
He tries to convince himself he wants to move on, even saying "Esto es pa' olvidarte, échame un cable" (This is to forget you, help me out), but he can't stop thinking about her. He remembers very specific things, like her belly button piercing, and admits he's made mistakes, like trusting her when she said she wasn't with the other guy. He knows he's being played—"Qué fácil soy de engañar" (I'm so easy to fool)—but he also admits he'd fall for it all over again. The whole song is this back-and-forth between knowing he should forget her and admitting he doesn't actually want to.