Ganado literally translates to 'livestock' or 'cattle', but in modern Spanish dating slang, it is used humorously to describe a 'roster' of people you are casually seeing.
In the lyrics, the singer laments his breakup by saying, "Y tú ya traes nuevo ganado" (And you already bring a new roster). He uses this clever double meaning to point out how quickly his ex moved on to a whole new group of suitors.
This song is a hilariously blunt and messy breakup anthem. Eden Muñoz is heartbroken after being someone's "casi algo" [almost something], realizing he was never the main guy, just the "por mientras" [in the meantime]. Since the breakup, he's been on a mission to forget her, dating so many people he says he's gone through the whole alphabet of names: "Me acabé el abecedario, desde la A hasta la Z" [I finished the alphabet, from A to Z]. But it's not working. He's even looking for her clone on Tinder and drinking to make his dates seem more interesting.
He's decided that since being a good guy didn't work out, he's just going to be a jerk now. He declares, "En vez de arreglar corazones vo'a romperlos" [Instead of fixing hearts, I'm going to break them]. But underneath all the tough talk, he's a mess. He admits he needs a psychologist, or maybe just some glasses "pa' ver que tú no me quieres como yo" [to see that you don't love me like I love you]. He's still got her photos saved while she's already moved on, and he ends the song desperately asking her for tips on how to forget someone so easily. It's a perfect song for when you're feeling down but also want to laugh at how dramatic heartbreak can be.