Vacílala comes from the verb vacilar, which has several meanings depending on the context and region. In this song, it's used in a more informal, colloquial sense, meaning to
Becky G spends this whole song refusing to keep score. It opens with "Papi, llevo todo el día / Preguntándome por qué habremos peleado" ("Baby, I've spent all day wondering why we fought"), and by the third line she has already conceded the argument on purpose: "Que sea batalla perdida" ("Let it be a lost battle"). Losing is the cheaper option, and she says why in the bluntest line here, "Porque no aguanto no tenerte a mi lado" ("Because I can't stand not having you next to me"). Pride gets no speech either, just a shrug: "Se queda en la mitad?" ("It just sits there in the middle?").
Her fix is not a conversation. It is the dance floor, asked for as a short list of favours: "Ven, regálame un besito" ("Come on, give me a little kiss"), then "¿Qué tal si hacemos las paces?" ("How about we make up?"), then "La bailamos apretaito' / Hasta que el mal tiempo pase" ("We dance it close until the bad weather passes"). That last one is the title, and it turns the usual storm metaphor inside out. Bad weather is normally something you wait out indoors; here you put a cumbia on and dance until it stops. The "Vacílala" she keeps calling over the outro is nearer to "have fun with it" than to any real instruction, which is roughly how seriously this song wants you to take a fight.