The word "ubrania" is plural, "ubranie" singular, but both mean multiple items of "clothing". "Ubranie" (odzienie, odziewek, SZATA) may mean everything you wear at any given moment, or well coordinated set of several items, like outfit.
Rarely, "ubranie" refers to a single men's suite (garnitur) or women's suite (kostium, garsonka). The word "ubrania" may also refer to the entire content of the closet, like wardrobe (garderoba).
The retail name for ubrania is "odzież" (odzież damska, męska, dziecięca).
"Ubrania" are often called "rzeczy" (several), or "rzecz" (one item of clothing).
There is a saying in Polish: "Nie SZATA zdobi człowieka"... (we know it does :-)