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.
Ever wanted to run into an ex just to show off how fantastic you look without them? That is the exact mood Dominican-American star Prince Royce brings to "Si Supieras" (If You Knew). Right out of the gate, he taunts an old flame who thought leaving would destroy him. Instead of moping, he brags that she would fake a polite smile while burning with jealousy: "Fingirías tu sonrisa / Mientras por dentro te mueres de envidia / Ver como otra me acaricia" ("You'd fake your smile / While inside you die of envy / Seeing another woman caress me"). He drops a cool English "chill" right in the middle of his vocals to tell her to calm down, because he is completely unbothered.
My absolute favorite part is how hilariously petty his proof of moving on gets. He does not just say he is happy; he brags about his skincare. He sings, "Si tu supieras que no tengo ni una ojera / Que contigo el insomnio se marcho / Ahora duermo mejor" ("If you only knew that I don't have a single dark circle under my eyes / That insomnia left with you / Now I sleep better"). The Spanish word ojera refers to the dark bags or rings you get under your eyes when you are exhausted or stressed. Losing her literally fixed his sleep schedule! Now he answers to nobody ("Ahora hago lo que quiera, sin tener que darte explicación" [Now I do whatever I want, without having to give you an explanation]), proving that sometimes the ultimate revenge is simply a solid eight hours of rest.