Sdolcinata literally translates to "overly sweet" or "sugary", but it's often used to describe someone or something that is excessively sentimental, cheesy, or sappy.
In the song, ANNA uses it to describe a girl named Dalia who is being overly affectionate or dramatic, to the point where it's almost sickening. The line "Fa la sdolcinata, quasi mi viene una caria" (She acts all sweet, it almost gives me a cavity) perfectly captures this feeling of something being so saccharine it's off-putting.
ANNA opens by refusing to be sensible about it: "Io non resto a casa a piangere, siamo sempre outside" [I'm not staying home crying, we're always outside]. By Sunday morning the bill arrives, and she is blunt about the state she is in: "Domenica mattina sto come Frankenstein" [Sunday morning I look like Frankenstein]. The English title phrase is the whole argument. She sings "Lasciami stare, sono white girl wasted" [Leave me alone, I'm white girl wasted] like a label she is happy to wear, then follows it with "Non mi so, non mi so comportare da lady" [I don't know, I don't know how to act like a lady], which lands closer to a boast than a confession.
The second verse turns the camera on somebody else. A girl called Dalia "Fa la sdolcinata, quasi mi viene una caria" [acts all sugary sweet, it almost gives me a cavity], and her boyfriend is dismissed in a single line: "Ti sei fidanzata col primo scemo che capita" [You got together with the first fool who came along]. The one flicker of self-awareness arrives just before the chorus returns: "Non farmi foto se sto nel locale" [Don't take photos of me when I'm in the club], because "C'è un'alta percentuale che sono white girl wasted" [There's a high chance I'm white girl wasted]. She knows how the night goes. She would rather it were not filmed.