This is the 412th most frequent Russian word.
мужчин
The word "мужчин" is the genitive plural form of "мужчина," which means "men" or "of men" in English.
The word "мужчин" is in the genitive plural form, used here to indicate possession or a quantity.
В автобусе было много мужчин.
There were many men on the bus.
The word "мужчин" is in the accusative plural form, used as the direct object of the sentence.
Я наблюдаю этих мужчин в парке.
I observe these men in the park.
The word "мужчин" is in the genitive plural form, used after a numeral or quantifier.