Jangueo is quintessential Puerto Rican slang, derived directly from the English phrase "hanging out". It's a cornerstone of reggaetón culture, meaning to party, chill, or hang out with friends.
In "Un Verano Sin Ti", Bad Bunny uses it to show how heartbroken he is. He sings "yo casi no jangueo" (I almost never hang out) to explain that while he's normally a homebody, the pain of the breakup now pushes him to go out every night just to distract himself.
This song is the ultimate soundtrack for a summer heartbreak. Bad Bunny walks us through the confusing aftermath of a relationship that just… ended. He admits he doesn't know what happened, saying, "Otro amor que de repente fracasó" [Another love that suddenly failed]. He's stuck inside his own personal raincloud while everyone else is enjoying the sunshine: "En mi cuarto está lloviendo y afuera está el sol" [It's raining in my room and it's sunny outside]. He even apologizes for not being the man his ex deserved, with the brutally honest line, "Yo quizá madure pero en otra vida" [Maybe I'll mature, but in another life].
He tries to convince himself he's fine, even saying "La estoy pasando bien / No te voy a mentir" [I'm having a good time / I'm not going to lie]. But he immediately follows it up by admitting her name keeps him awake at night. He's even started going out all the time, which he says he never used to do, just on the off chance he might see her. The whole mood is summed up perfectly in one line: "Mañana voy a terapia / Hoy voy pa'l teteo" [Tomorrow I'm going to therapy / Today I'm going to party]. It's that feeling of knowing you should deal with your sadness, but choosing to go out and dance instead.