Pupila literally translates to "pupil" of the eye. While it's a common anatomical term, its use in this context is quite striking and less common in everyday song lyrics.
In the lyrics, "había visto la pupila salir a disparar" (I had seen the pupil go out to shoot), it's a vivid and somewhat metaphorical way to describe witnessing violence or a dangerous act. It implies seeing the intense focus in someone's eyes just before they act, making it a memorable and intriguing word choice.
Get ready to meet El Compa Zera! This song is a high-energy corrido that tells the story of a man who knew from a young age he was destined for something big. Even in elementary school, he told his friends he'd be important, and they believed him!
He talks about leaving home at 15 to cross the border, starting with honest work before getting into other things. He quickly learned the ropes, saying, "cuando tenía 10 años y aportando había visto la pupila salir a disparar" [when I was 10 years old and contributing, I had seen the pupil come out to shoot]. He built up his clientele, made money, and eventually returned to his hometown with international clients. Now he's the boss, managing things from his phone, with houses, ranches, cars, and weapons. But for all his success, he says his greatest wealth is his united family: his wife, children, and parents. He's also a fan of firearms, with a favorite "super de los fueron unas cartas no se le ve la vía a manter as a vessel porque está el incidente de montilla sin escudarse en las calles ponía puedo presentarme" [a super that was some cards, you can't see the way to maintain it as a vessel because the Montilla incident is there without shielding itself in the streets I could introduce myself]. He's grateful for everything he has and plans to enjoy his ranch one day.