Maltratando comes from the verb maltratar, meaning "to mistreat" or "to hurt". It's a strong word that conveys suffering or ill-treatment.
In this song, the artist uses it to describe how distance is "maltratando" (mistreating/hurting) their relationship. It personifies distance as an active force causing pain, making the listener feel the emotional toll of being apart.
This song, "A Distância Tá Maltratando" by Leo Foguete featuring DG e Batidão Stronda, is all about that tough feeling when you're far away from someone you care about. The singer is really missing someone who has moved to a new city. They ask, "Quando é que vem aqui?" [When are you coming here?] and say they are "contando as horas pra te ter de volta" [counting the hours to have you back].
The distance is really getting to them, even though they admit it "fortalece a nossa relação" [strengthens our relationship]. But they're at their limit, declaring, "eu não 'to mais aguentando" [I can't take it anymore]. They're so desperate to see this person that if a plane ticket is too expensive, they'll just take the bus: "Se de avião 'tá caro, eu vou de busão" [If by plane it's expensive, I'll go by bus]. It's a sweet and relatable feeling of longing, showing how much they want to close that gap between the North and the South of Brazil.