Rolé de boa is a very common Brazilian Portuguese slang phrase that literally translates to "a chill stroll" or "a good time". It's used to describe a casual, relaxed outing or hangout with no strings attached.
In the context of the song, the singer and their partner had a "combinado" (agreement) that their encounters would be just a "rolé de boa" – a casual, no-commitment hookup. However, as the lyrics reveal, feelings started to develop, making it more than just a simple, chill hangout.
Dilsinho opens by admitting he doesn't have the maturity he thought he had, and everything that follows shows exactly what he means. The setup is one of those late-night arrangements: he picks someone up "Onze e pouquinho" [a little past eleven], no promises attached, just two people sweaty in bed, talking about life, with no love and no goodbye kiss planned.
The chorus is where the plan falls apart. "Era pra ser só mais um rolé de boa" [it was supposed to be just another casual thing], he admits. "Mas quando rola a química a noite voa" [but when there's chemistry the night flies]. Nobody invited feelings into this one. "Mas o meu coração entrou sem ser chamado" [but my heart came in uninvited], and that line says more than the rest of the confession combined. He tried to keep things cold. It didn't stay that way.