Rescatate is a colloquial term, particularly common in Argentina, meaning "snap out of it" or "get it together." It's an informal command to tell someone to be careful or to stop doing something foolish.
In the song, it's used in the line "Plo-plo-plo, guacho, rescatate, eso no son tiro', pa', son los caños de escape." Here, the artist is telling someone to realize that the sounds they're hearing aren't gunshots but rather the backfiring of car exhausts, highlighting a street-smart awareness and a call to distinguish reality from perception in a barrio setting.
Tiago PZK's "Flow De Barrio" throws you right into the heart of his neighborhood, showing you what life is like for the "guachines" [kids] growing up there. He talks about dreams of being on stage, but also the reality of going to the "comedor comunitario" [community kitchen]. It's a stark contrast, with some kids going to bed early and "otros con el fierro en la mano" [others with a gun in hand].
The song really captures the energy of the streets at night. He mentions buying beer at 3 AM and hoping the police don't "poner las norma'" [make the rules]. There's a sense of constant movement, with cars low to the ground and the sounds of the neighborhood, sometimes mistaken for gunshots: "Plo-plo-plo, guacho, rescatate / Eso no son tiro', pa', son los caños de escape" [Plo-plo-plo, dude, chill out / Those aren't gunshots, bro, those are exhaust pipes]. It's a vivid look at a community where people are working hard, some are partying, and everyone is trying to make it, often under the radar, hoping "que la gorra no nos vea" [the cops don't see us].