This is the 229th most frequent Polish word.
polacy
"Polacy" means "Poles" or "Polish people" in English.
The word 'Polacy' refers to the inhabitants of Poland as a national group.
Polacy są dumni ze swojej historii.
The Polish people are proud of their history.
Here, the word changes in form ('Polaków', which is the genitive plural form of 'Polacy') indicating that 'Polacy' is declined based on grammatical case in Polish.
Wielu Polaków mieszka za granicą.
Many Polish people live abroad.
In this question, 'Polacy' is used as the subject of the sentence and refers to the group collectively.