This is the 7839th most frequent Polish word.
mig
A "moment" or "instant."
Here, 'mig' refers to a very short period of time, emphasizing the quickness of the action.
Zrobiła to w mig!
She did it in a flash!
In this context, 'MIG' refers to a specific brand or type of military aircraft, being a proper noun.
Samolot wojskowy MIG wystartował z lotniska.
The military MIG aircraft took off from the airport.
Again, 'mig' is used poetically here to indicate the briefness or fleeting nature of time.