Puntada literally means "stitch" (as in sewing) or "prick." However, in this song, it's used in the idiomatic expression "nomás de puntada," which means "just as a hint" or "just as a guess."
It's an interesting word because it shows how a common word can take on a completely different meaning in an idiomatic phrase. The singer uses it to say he predicted someone's destiny almost casually, as if making a quick, offhand remark, and it turned out to be true.
Yeison Jimenez's "La Ley De La Vida (En Vivo)" is a really blunt look at how the world works, especially when it comes to money and relationships. He sings, "Uno vale según lo que tiene / Por desgracia es la ley de la vida" [One is worth according to what one has / Unfortunately, that's the law of life], which sets the tone right away. It's all about how people treat you better if you have wealth, even offering you more than you need: "Traes caballo y te ofrecen la silla" [You bring a horse and they offer you the saddle].
He also touches on ambition and betrayal in love, saying, "Al dejarte algo malo te dieron / Porque a nadie le gustan traiciones" [When they left you, they gave you something bad / Because nobody likes betrayals]. It's a pretty cynical view, but he also offers a kind of tough love. He can sympathize with your pain, "Puedo creerme que siento tus penas" [I can believe that I feel your sorrows], but ultimately, he can't fix your problems, only offer a few coins. He even predicted a past love's destiny, saying, "No llegaste a casarte conmigo / Y no creo que te mueras casada" [You didn't marry me / And I don't think you'll die married], which is a pretty bold statement!