This is the 7137th most frequent Russian word.
британка
"Британка" means "British woman" in English.
'британка' is used here to refer to a female person from Britain.
Моя подруга — британка.
My friend is a British woman.
'британка' refers here to something 'British', in this case, indicating a type or origin relevant to the term's femininity.
Собака британка находится в соседней комнате.
The British dog is in the next room.
'британка' could signify an item or concept described as British, contextualized by the feminine.