Secuelas translates to "aftermath" or "consequences," often in the same way English uses "sequelae" to talk about the after-effects of an illness or injury. It’s a powerful, dramatic word you don't hear every day.
In the song's title, "Secuelas de Amor," Carin León uses it to describe the lasting emotional scars and pain from a failed romance. He sings that what people see in him are the "secuelas de olvido" (the aftermath of being forgotten), a poetic and intense way to describe heartbreak.
Carin Leon is not holding back in this song. He kicks things off by getting straight to the point: "Maldito tu amor / Mil veces maldito" (Cursed be your love / A thousand times cursed). This isn't a sad breakup song; it's a furious declaration of regret over a one-sided love affair. He says his current state is just the "secuelas de olvido" (after-effects of forgetting) from a love that was "muy mal correspondido" (very poorly reciprocated).
He regrets everything, from the sweet nothings he whispered to the time he invested. He even regrets looking like a fool with a "mano sudada" (sweaty hand), a perfect detail about being nervous and in love. The best line, though, is when he says he took his one chance at happiness and "Se la tiré al perro" (I threw it to the dog). It's a blunt and kind of hilarious way to say he completely wasted it on the wrong person.