Mañas translates to 'tricks' or 'cunning ways'. It's a colloquial term often used to describe someone's sly habits or manipulative tendencies, especially when they're trying to get their way.
In the song, the singer uses it to call out their ex, saying, "Yo conozco tus mañas" (I know your tricks). It implies that the ex is trying to play games or pretend they don't care, but the singer sees right through their act. It's a fun, slightly sassy word that adds a lot of character to the lyrics.
Los Dareyes De La Sierra's "NI SUMA NI RESTA" is a super direct song about someone who's completely over an ex! The singer knows their ex is still trying to get their attention, even though the ex pretends not to care. Lines like "Ay, babe, tú no me engañas, yo sé que sí me extrañas" [Oh, babe, you don't fool me, I know you miss me] and "Dices que no te acuerdas, yo conozco tus mañas" [You say you don't remember, I know your tricks] really set the tone.
Our singer isn't having any of it. They're done with the games and the drama, calling the ex a "dolor de cabeza" [headache] and saying, "Tú a mí no me interesas, aquí ni sumas ni restas" [You don't interest me, here you neither add nor subtract]. It's a blunt and catchy way to say, "You mean nothing to me anymore!" If you've ever had an ex who just wouldn't quit, you'll definitely relate to this one.