I’m staying at a dorm and it says "Students are not permitted to play any type of musical instrument in the dorms. Those who wish to play or practice must muffle their musical instruments."
What is muffle?
it’s an acoustic guitar

Muffling is like dampening the sound on an instrument. I play percussion and an example of muffling a percussion instrument (like the snare drum) would be putting a little black rubber pad (idk that’s what we have at our school) on the snare head to make it quieter. I could give a better explanation if I knew you’re instrument!