Jangueando is a super fun, modern slang word you'll hear a lot in Latin urban music. It's the Spanish version of the English phrase "hanging out", making it a perfect example of Spanglish where English words are adapted into Spanish grammar.
In the song, KAROL G uses it to say, "Hoy estás jangueando con ella" (Today you're hanging out with her). She's setting the scene, imagining her crush out with his current girlfriend while she plans to win him over.
Have you ever seen someone across the room and thought, "What if?" That's exactly where KAROL G is in this super fun merengue track. She's spotted someone she likes, but there's one small problem: he's with his girlfriend. Instead of being sad, she launches into a full-on fantasy about what could have been. She sings, "¿Qué hubiera sido? / Si antes te hubiera conocido" (What would it have been? / If I had met you before), imagining they'd be dancing together, and definitely "No como amigos" (Not as friends).
KAROL G is feeling bold and isn't shy about comparing herself to the other woman. She's convinced the girlfriend, while beautiful, is too timid and can't compete. She even gets a little wild, saying, "Con estas ganas que tengo yo / Me atrevo a comerme a los dos" (With this desire I have / I dare to eat you both up!). She's so sure they're meant to be that she's already planning their future, hilariously declaring, "Estoy esperando el primer descuido / Pa' presentarte como mi marido" (I'm waiting for the first slip-up / To introduce you as my husband). It's a playful and confident song about wanting what you can't have... at least for now.