This is the 813th most frequent Swedish word.
männen
The men.
Here, 'männen' is the definite plural form of 'män,' which means 'men' in Swedish.
Männen pratar högt.
The men are talking loudly.
In this sentence, 'männen' is again the definite plural, used to specify which men are referred to—the ones by the park.
Jag såg männen vid parken.
I saw the men by the park.
'Männen' here is used as the subject of the sentence, referring to a specific group of men previously known in the context.