Prepotencia translates to "arrogance" or "haughtiness." It's a strong and less common word than, say, "orgullo" (pride), making it more impactful and memorable.
In the song, the singer directly blames his partner's "orgullo maldito y tu prepotencia" (cursed pride and your arrogance) for destroying their relationship. This word perfectly captures the negative trait that led to the breakup, making it a key element in understanding the song's emotional core.
This is the ultimate "I'm so over you" song. Silvestre Dangond isn't crying over a breakup; he's celebrating his escape from a relationship with someone he sees as totally self-absorbed. He tells his ex, "No eres más que vanidad" (You are nothing more than vanity) and that she's mistaken to think "que el mundo gira a tus pies" (that the world spins at your feet). He's had enough of her pride and arrogance destroying his heart.
Now, he's finally free and making it crystal clear that this is the end. The whole song is a powerful declaration: "Y esta será / La última vez que me mires / La última vez que me toques" (And this will be / The last time you look at me / The last time you touch me). He's done faking it, done with her false apologies, and ready to breathe with tranquility. He even predicts she'll be the one left crying when she has to face her own loneliness.