Guachita is an endearing term, a diminutive of guacha, which is a colloquial and affectionate way to refer to a young woman or girl, particularly in some Latin American countries like Chile and Argentina. It's similar to saying "my girl" or "my little one" in English, often implying a sense of familiarity and affection.
In the song, Manuel Turizo uses Mi guachita, ¿dónde está? (My girl, where are you?) to express a longing and a familiar connection with the person he's singing about. It's an interesting word because it's a regional slang term that adds a unique, intimate, and playful flavor to the lyrics, making it stand out from more common terms of endearment.
Manuel Turizo spends this one drinking through a breakup and then calling her anyway. The hook is almost cheerful about it: "Curo mis heridas con alcoho-o-ol" (I heal my wounds with alcohol), with the vowel stretched out until it sounds less like a confession than a party chant. He opens by admitting he never meant to get here at all, "Tanto que decía que no iba a envolverme" (I kept saying I wasn't going to get involved), and by the second verse he is "Me la paso bebiendo mirando tu foto" (I spend my days drinking, staring at your photo). The question he keeps asking, "Dime quién no ha roto un corazó-ó-ón" (Tell me who hasn't broken a heart), is less a defence than a shrug.
Martinwhite takes the back half and drags the whole thing somewhere messier and funnier, dropping into Chilean slang mid-thought: "Nos enredamos, bebé, ¿me cachai?" (We get tangled up, babe, you know what I mean?) and "¿Que si aún te pienso? Pues sipo" (Do I still think about you? Well, yeah). He remembers mornings in Viña del Mar, wounds they reopened on purpose, and then lands the line the whole song has been circling: "Las ganas son más grandes que la consciencia" (The craving is bigger than the conscience). That is the honest version of the chorus. The alcohol was never really the point.