Ahórratelo is a strong, direct command meaning "save it" or "spare me." It's formed from the verb ahorrar (to save) and the pronouns te (you) and lo (it), making it a concise and impactful phrase.
In the song, the singer uses ahórratelo to dismiss unwanted advice about a new relationship. She's telling the person to keep their warnings to themselves, asserting her independence and confidence in her own choices. It's a powerful expression of self-reliance.
Miriam Cruz opens this one already annoyed: someone's about to give her a lecture about the guy she's seeing, and she's not having it. "Ya sé que ando con alguien peligroso" [I know I'm with someone dangerous], she sings, "Que tiene fama de don Juan y mentiroso" [Who has the fame of Don Juan and a liar]. She knows exactly what she's walking into. The chorus is where the song earns its title: "Yo me cuido sola cuando me enamoro" [I take care of myself when I fall in love], "Si sale el corazón herido pues ni modo" [If the heart comes out wounded then no way]. If it goes wrong, that's on her, not on whoever's trying to warn her off.
There's a sharper edge in the second verse, where she turns the warning back on the person giving it. "Ustedes dos tuvieron algo en su momento" [You two had a thing back then], "Y si terminaron mal ¿por qué va a pasarme igual?" [And if they ended badly, why is the same going to happen to me?]. It's not naive optimism, it's a refusal to let someone else's bad breakup decide her own relationship. By the end she's blunt about it: "Si no te hizo feliz no te preocupes por mí" [If it didn't make you happy don't worry about me]. She's heard the advice, she's not taking it, and she's not apologizing for that either.