Guachas is a slang term, particularly common in Argentina (KHEA's home country), that refers to young women or 'girls'. It's similar to 'chicks' or 'babes' in English, often used in a casual or informal context.
In the song, the line "Que está con dos guachas de party por Brickell" (That he's with two girls partying in Brickell) immediately sets a scene of a party and casual encounters. This word is interesting because it's not a standard dictionary term like 'chicas' or 'mujeres', offering a glimpse into regional slang and adding a specific, youthful, and somewhat edgy flavor to the lyrics that is characteristic of trap music.
"Volverás" is KHEA's take on a breakup where pride is doing the talking. He's just heard that his ex is out partying in Brickell, and instead of chasing her, he leans into what he already knows: she called him fake promises before, and sooner or later, she'll be the one coming back to him.
The verses go over what went wrong. He believed her when she said things would be different, and she let him down anyway. Now he's the one comparing notes with her mother about how badly it ended, and reminding her that she was never really honest with him.
The chorus is the whole point of the song: he'd rather be alone than stuck in a relationship where he's constantly the one being disrespected. It's less about missing her and more about refusing to settle for bad company again.