noun
single room; own room
Refers to a room occupied by one person, either a private room in a shared house or a single-occupancy hotel room.
このアパートは一人部屋が三つあります。
This apartment has three single rooms.
ホテルで一人部屋を予約した。
I booked a single room at the hotel.
個室 is a more formal term for a private room, often used in hospitals, offices, or restaurants, while 一人部屋 is a straightforward term for a single-occupancy room in a house or hotel.
Compound of 一人 (ひとり, 'one person') and 部屋 (へや, 'room').