A trick is to translate man as "one".
You can understand this better with a couple of examples:
Man kauft Dinge, die man nicht braucht
One buys things that he doesn’t need
Kann man hier rauchen?
Can one smoke here?
Man is not declined (it doesn’t change) and only can be used in the nominative singular.
The use of the pronoun “man” is very common when the person that is carrying out the action is not important. This structure is more common than the passive in every day language.