Branchie translates to "gills". It's an unexpected and vivid word to find in a rap song, immediately grabbing attention.
In the lyrics, Salmo says, "Non preoccuparti che in 'sta fogna nasci con le branchie" (Don't worry, in this sewer you're born with gills). This metaphor suggests that in a harsh or corrupt environment (the "sewer"), one quickly adapts and develops the necessary tools to survive, just as a fish needs gills to breathe underwater. It's a powerful image of resilience and adaptation.
Salmo raps about the cost of the life he chose. He was born ready for a hard world ("born with gills" in the sewer), and now that he's famous he still feels like he's fighting for air, calling fame "hell" and admitting he sometimes wants to disappear.
The chorus is the heart of the song: "people like me will die alone." He pictures himself as a wolf howling at a storm, wrapped in his own darkness, pushing everyone else away rather than let them in.
The second half gets more personal and darker, touching on doubt, temptation, and the fear that this restless drive might destroy him before it's done anything good. Music becomes his way of staying alive: writing, dying, and coming back to life through it, over and over, one more "Monday" at a time.