Melindrada describes someone who is easily offended or overly sensitive, often in a delicate or prim way. It's a less common word than simply "ofendida" (offended), carrying a nuance of being overly delicate or even a bit fussy about slights.
In the song, the singer declares, "Não sou de ficar melindrada" (I'm not one to get easily offended/touchy). This line is interesting because it immediately follows a situation where her partner is dancing with someone else, setting up a contrast between her stated resilience and the brewing conflict. It hints at her strong personality and refusal to be a passive victim.
"No Meio Do Salão" is Maria Rita drawing a line on the dance floor. She opens by naming exactly what's at stake—"Eu te trouxe pro samba, para comigo dançar" [I brought you to the samba, to dance with me]—before the warning: "Você se atreve, dança com outra por quê?" [You dare, why dance with another?]. If it turns into a scene, she wants him to stay for it, not sneak off: "Se houver bate boca, no meio do salão, não quero que vá embora" [If there's an argument, in the middle of the hall, I don't want you to leave]—"quero que fique pra ver o que vai acontecer" [I want you to stay to see what will happen].
She's not the type to sulk about it, either. "Não sou de ficar melindrada" [I'm not one to get offended], she says, "mas hei de dizer, comigo não tem malandragem" [but I must say, with me there's no trickery]. The line sharpens as the song goes on: "se o bicho pegar dessa vez, vai sobrar pra você" [if things get ugly this time, you'll pay for it]. By the back half she's already rehearsing the aftermath, repeating "eu não vou me arrepender do que vai acontecer" [I won't regret what happens] until it sounds less like a threat than a decision she's already made—set, all the while, to a beat built for dancing.