noun
reserved seat
A seat that has been booked in advance, such as in a theater, on a train, or at a restaurant.
予約席は前方の三列です。
The reserved seats are the three rows at the front.
この列車は全席予約席です。
All seats on this train are reserved.
自由席 is an unreserved seat, available on a first-come, first-served basis.
Compound of 予約 (reservation) and 席 (seat).