Guest Room
A guest's room is the guest room (the room you put guests in, duh!).
きゃくしつ
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.
大すきなアイドルと、ろ天ぶろ付の客室にとまることがゆめなんです。
My dream is to stay in a guest room attached to an open air bath with the idol I love.
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。
In this hotel, all the guest rooms have concierge service.
ちょうど客室のリフォームが終わったところなんですの。是非うちにいらして、ご意見を聞かせてくださいな。
I just finished renovating the guest room. Come over and tell me what you think.