A somewhat traditional or literary word for a bedroom or sleeping room. In modern everyday speech, 寝室 (しんしつ) is more common.
My grandmother is resting in the upstairs bedroom.
The inn's sleeping room had tatami flooring.
Compound of 寝 (ne, 'sleep') and 間 (ma, 'room' or 'space'). The exact historical derivation is uncertain, but the spelling is conventionally associated with a sleeping room.