This is the 8807th most frequent Russian word.
поляки
Polish people.
Here, 'поляки' is the subject of the sentence and refers to people of Polish nationality.
Поляки посетили музей.
The Poles visited the museum.
In this sentence, 'поляками' is in the instrumental case, denoting the people someone interacted with.
Вчера я разговаривал с поляками на конференции.
Yesterday, I spoke with Poles at the conference.
Here, 'поляков' is in the genitive case, describing a group of people defined by their nationality.