https://en.wiktionary.org/wiki/man#German_Low_German
From Middle High German man, from Old High German man, from Proto-West Germanic *mann, from Proto-Germanic *mann- (“man”), probably ultimately from Proto-Indo-European *mon-. Originally the same word as Mann (“man”), which see for more. The same construct in Dutch men, French on.
man
one, you (indefinite pronoun; construed as a third-person singular)
Man kann nicht immer kriegen, was man will.
You can’t always get what you want.
Manchmal muss man Kompromisse machen.
Sometimes one must compromise.
they, people (people in general)
Zumindest sagt man das so…
At least that’s what they say…
someone, somebody (some unspecified person)
they (some unspecified group of people)
Usage notes
Man is used in the nominative case only; for the oblique cases forms of the pronoun einer are used. For example: Man kann nicht immer tun, was einen glücklich macht. — One cannot always do what makes one happy.
Since man derives from the same source as Mann (“man; male”), its use is considered problematic by some feminists. They have proposed alternating man and the feminine neologism frau, or using the generic neologism mensch. This usage has gained some currency in feminist and left-wing publications, but remains rare otherwise.
In the sense of “someone,” man is often translated using the passive voice (“I was told that…” rather than “someone told me that…”).
Etymology 2
From Middle Low German man. A contraction of Old Saxon newan (“none other than”). Compare a similar contraction in Dutch maar (“only”).
Adverb
man
(colloquial, regional, Northern Germany) just; only
Komm man hier rüber!
Just come over here!
Das sind man dreißig Stück oder so.
These are only thirty or so.
Czech Language Lessons & Translations 