Cabrón is a versatile and strong Spanish slang term. While it can literally mean 'goat', in colloquial use, it often translates to 'bastard' or 'jerk', conveying a sense of being a bad person or having acted poorly.
In the context of this song, the singer says, "Me he sentido un cabrón" (I've felt like a bastard/jerk). This reveals a moment of deep self-reflection and regret, where he acknowledges his own negative actions or feelings in the aftermath of a relationship. It's an emotionally charged word that adds significant weight to the lyrics.
Dani Martín turns a breakup into a blackout. "Hoy ha habido un apagón" (There's been a blackout today), he sings, then explains exactly how short the good part was: "La luz nos ha durado lo que dura un café" (The power lasted us as long as a coffee). A plane falls out of the sky a few lines later. The storm just keeps going.
By the chorus he's given up on metaphor and says the thing plainly: "Te llevaste una parte de la ciudad, no encuentro mi lugar" (You took a part of the city, I can't find my place). Madrid gets said three times in a row, like he's testing whether the name still means what it used to.