Herirte means "to hurt you." It's the infinitive verb "herir" (to hurt) combined with the pronoun "te" (you).
In the song, Angela Aguilar uses this word to express her reluctance to cause pain, even as she delivers the difficult news that she no longer has feelings for someone. She sings, "Que no es mi intensión herirte" (That it's not my intention to hurt you), highlighting the emotional weight of her message.
Ángela Aguilar sings a breakup confession delivered with unusual gentleness. She opens by asking to be understood before she even says the hard part: "Yo quiero que me comprendas" ("I want you to understand me"), then admits she can't explain the shift herself: "Ni yo misma lo comprendo" ("Not even I understand it"). The chorus states the plain fact without cruelty: "Tú a mí ya no me interesas" ("You no longer interest me").
The second half turns the ending into a kind of release for both of them. She hopes he finds someone new — "Yo quiero que te enamores, que encuentres otro cariño" ("I want you to fall in love, that you find another love") — and asks forgiveness for a truth she knows will sting: "Que por ti ya nada siento" ("That for you I feel nothing"). It's a song about closing a chapter honestly instead of dragging it out.