This is the 1840th most frequent Polish word.
częstochowie
"Częstochowie" is the locative form of "Częstochowa," referring to the city of Częstochowa in Poland when used in certain grammatical contexts (e.g., "in Częstochowa").
Here, 'Częstochowie' is the locative case of 'Częstochowa', indicating location or place (in Częstochowa).
Mieszkam w Częstochowie od pięciu lat.
I have been living in Częstochowa for five years.
In this context, 'Częstochowie' again serves as the locative case, specifying the location (in Częstochowa).
Byliśmy na pielgrzymce w Częstochowie.
We were on a pilgrimage in Częstochowa.
The usage of 'Częstochowie' here demonstrates its locative case role to describe the location where the meeting took place (in Częstochowa).