This is the 77th most frequent German word.
müssen
"To have to" or "must."
Here, 'muss' is used to express an obligation or necessity that applies to the subject 'ich' (I).
Ich muss jeden Tag zur Arbeit gehen.
I have to go to work every day.
Here, 'muss' is used to indicate a necessity or requirement for the subject 'er' (he).
Er muss morgen früh aufstehen.
He has to get up early tomorrow.
Here, 'müssen' is used in the first-person plural form to express a responsibility or obligation.