"This district does not have a name."

Translation: Quận này không có tên.

[CBlondie]

Why doesn't this sentence need một for a name

[Komerinam]

In Vietnamese, we don't use một like "a".
In English, a sentance always has an "a" or "the" but in VN, it doesn't always need those, but only when you want to point something or its number out.