It's funny because in my native tongue - Filipino, if you think of the word "gatas" just the word itself and not being "pluralized" in this sentence, in my native language it means milk. And then this sentence has leite in it which also means milk.
Gender does not swich. Os gatos means male cats. As gatas means female cats. Gata and gatas is also slang for an atractive woman, but it is very common slang
I was also confused. I wrote it correctly but I though the translation will be " babies drink milk". Why is it o gato for singluar and as gatas and not os gatos for plural?
I live in Brazil currently, and they use gata as a slang for babe or hot. For example: Ela é uma gata=She is a babe. But the literal translation is female cat.
cats drink milk would be a generic statement, that would be gatos bebem leite or gato bebe leite or o gato bebe leite. I would say gato bebe leite is the most used when doing a general statement.