This is the 102nd most frequent Bulgarian word.
руски
Russian
In this sentence, 'руски' is used as an adjective to describe a novel of Russian origin.
Той чете руски роман.
He is reading a Russian novel.
In this case, 'руски' is used as an adjective to describe the nationality of the citizens.
Моите съседи са руски граждани.
My neighbors are Russian citizens.
Here, 'руски' serves as an adjective to specify the type of language being studied, Russian.