"Nā" literally means plural marked for "the". The word "nā" is used only for to denote definitive plural nouns.
"Aia nā mae pāʻani ma ka lumi moe" / "The toys are in the bedroom"
But you have to add the word "mau" before nouns to make it plural in most sentences.
"Aia kēlā mau mea pāʻani ma ka lumi moe" / "Those toys are in the bedroom"
That sentence would be translated into Hawaiian.