Guest Room
noun
A guest's room is the guest room (the room you put guests in, duh!).
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
自分の客室
one's own guest room
全ての客室
all of the guest rooms
ホテルの客室
hotel room
客室は広く、ベッドが二つありました。
The guest room was large and had two beds.
海が見える客室は、やはり高いです。
Sure enough, rooms with ocean views are expensive.
このホテルでは全ての客室にコンシェルジュサービスが付いてきます。
At this hotel, all the rooms have concierge service.