Plaquinha de aviso literally translates to "little warning sign" or "warning plaque." It's an interesting phrase because it combines the diminutive form "-inha" (making "placa" into "plaquinha"), which adds a touch of endearment or irony, with the practical concept of a warning.
In the song, the singer wishes the person came with a "plaquinha de aviso" to warn him about their deceptive nature and the heartbreak they might cause. It's a creative and memorable way to express regret and a desire for foresight in a relationship.
Ever been drawn to someone you know is bad news? That's the whole vibe of Gustavo Mioto and Wesley Safadão's "Plaquinha de Aviso"! The singer wishes this person came with a warning sign: "Você tinha que vir com uma plaquinha de aviso" [You should come with a little warning sign]. They're telling everyone to "Mantenha distância, cuidado com o sorriso" [Keep your distance, beware of the smile] because if their mouth touches yours, you're in trouble!
The singer knows this person is a player, saying "Na teoria era pra eu ser o titular, mas no fim de semana tem mais gente pra jogar" [In theory I was supposed to be the starter, but on the weekend there are more people to play]. Even though they almost believe the lies, especially when they say "me ama" [they love me], the singer admits, "Você mente muito bem" [You lie very well]. But here's the kicker: despite all this, they're still totally into them! "Você não presta, mas muito me interessa" [You're no good, but you interest me a lot] is the blunt, catchy truth of the song. It's a fun, honest look at being attracted to someone who's clearly trouble, but you just can't help yourself.