This is the 1232nd most frequent Polish word.
rosjan
"Rosjan" means "Russians" (plural) in English.
The word 'Rosjan' (genitive plural form) refers to a group made up of people of Russian nationality.
Spotkałem grupę Rosjan w parku.
I met a group of Russians in the park.
The word 'Rosjan' (genitive plural form) is used because the verb 'znać' governs the genitive case.
Nie znam osobiście żadnych Rosjan.
I do not personally know any Russians.
The word 'Rosjan' can also function as a shortened or colloquial form representing an individual Russian.