This is the 1727th most frequent German word.
freiwilligen
"Freiwilligen" means "volunteers" in English.
In this case, 'freiwillige' is used as an adjective describing 'Mitarbeit' (work) that is done voluntarily.
In vielen Organisationen gibt es auch eine freiwillige Mitarbeit.
In many organizations, there is also voluntary work.
In this sentence, 'Freiwillige' is used as a plural noun referring to people who voluntarily assist.
Viele Freiwillige helfen beim Bau des Gemeindezentrums.
Many volunteers are helping with the construction of the community center.
Here, 'Freiwillige' serves as a plural noun to specify individuals who choose to contribute their time without obligation.