This is the 12389th most frequent Polish word.
musza
"Musza" means "fly-like" or "of a fly" in English.
Here, 'musza' appears in a form related to action imperative or suggestion, reflecting the Polish verb 'muśić', implying movement.
Muś że zabawkę na półkę, a nie na podłogę.
Put the toy on the shelf, not on the floor.
Here, 'musza' is used as a verb form of 'musieć', meaning 'must' or 'have to', conjugated for the third person plural.
Musza zrobić swoje zadanie.
They have to do their assignment.
In this sentence, 'musza' is used as an adjective, describing something as relating to flies.