This is the 12372nd most frequent Polish word.
msze
"Msze" means "Masses" (religious ceremonies in Christianity).
Here, 'mszy' is the instrumental case singular form of 'msza', referring to a religious mass.
W niedzielę rano ludzie często uczestniczą we mszy.
On Sunday morning, people often attend mass.
'Msze' is the nominative plural form of 'msza', referring to multiple religious ceremonies.
Msze w trakcie świąt są bardzo uroczyste.
Masses during holidays are very solemn.
In this case, 'msze' functions as the subject of the sentence, denoting specific instances of the religious event.