Vencido translates to "defeated" or "vanquished". It's a strong and evocative word that carries a sense of finality and loss.
In the context of the song, the singer uses it to address a rival, telling him not to feel offended "después de ser vencido" (after being defeated). It highlights the rival's loss in love and the singer's triumph, making it a central theme of the song.
Joe Veras's "Vencido" is a really direct song where the singer is basically telling another man, "Hey, I've won, and you've lost!" He's not shy about admitting that he's now with the woman who used to be with the other guy. The singer even thanks God for this good fortune, saying, "gracias a dios porque a mí me tocó la dicha de tdt a quien fuese su mujer" [thank God because I had the good fortune to have who was once your woman].
He tells the defeated man not to be offended, but to understand that the woman doesn't want him anymore. The singer believes the other man neglected her, comparing a woman's love to a flower that needs care: "el amor es igual que una flor que si la descuido sin agua y sin calor se le puede morir" [love is like a flower that if neglected, without water and without heat, can die]. He's confident that he gives her a love no one else has, and she's chosen to stay with him, not wanting to be with anyone else. It's a pretty bold declaration of victory in love!