This is the 2559th most frequent Swedish word.
männens
"Men's" (possessive form of "män," meaning "men").
Here 'männens' is genitive plural, indicating possession and meaning 'of the men.'
Männens idéer förändrade samhället.
The men's ideas changed society.
In this sentence, 'männens' again acts as genitive plural, showing that the reactions belong to the men being referenced.
Jag såg männens reaktioner efter talet.
I saw the men's reactions after the speech.
Here 'männens' is genitive plural, attributing successes to the group of men.