Ileso means "unscathed" or "unharmed". It's a powerful and dramatic word to describe emerging from a difficult situation without any injuries.
In this bachata track, Prince Royce sings that he has "salido ileso de tu amor" (come out unscathed from your love). He uses this word to declare victory after a bad breakup, emphasizing that he has not only survived but is thriving, completely free from the emotional damage his ex tried to inflict.
This is the ultimate post-breakup song! Prince Royce is talking directly to an ex, and he's not holding back. The whole vibe is, "You thought you broke me, but look at me now." He imagines her seeing him happy with someone new and says she would "fingirías tu sonrisa / Mientras por dentro te mueres de envidia" (fake your smile / while inside you're dying of envy). It's a super confident and maybe a little petty way of declaring he's won the breakup.
The best parts are the specific details he uses to prove how much better his life is. He's not just saying he's happy; he's telling her "que no tengo ni una ojera / Que contigo el insomnio se marcho / Ahora duermo mejor" (that I don't even have dark circles under my eyes / that with you the insomnia left / now I sleep better). He's literally sleeping better now that she's gone! The song is a celebration of getting your life and your peace back, telling an ex that he's "salido ileso de tu amor" (come out of your love unharmed) and is finally free.