Man sagt, dass das Wetter morgen schön wird.
English: People say that the weather will be nice tomorrow.
In German, 'man' is an indefinite pronoun used to talk about people in general, similar to saying 'one', 'someone', or 'people'. It is always used with verbs in the third person singular.
Use 'man' in German when you want to make a general statement, give advice, or talk about what people usually do, without mentioning a specific person.
Man sagt, dass das Wetter morgen schön wird.
English: People say that the weather will be nice tomorrow.
Man muss jeden Tag Wasser trinken.
English: One must drink water every day.
Man lernt viel in der Schule.
English: You learn a lot at school.
Man darf hier nicht rauchen.
English: You are not allowed to smoke here.