Room
suffix
You'll see this attached to other words... like "waiting" or "guest." When you see this, you'll know it is a ___ room, making this word mean room (same as the kanji).
しつ
The reading is the on'yomi reading. Don't type the 〜 out when writing the answer. It's just there to let you know that there's usually something attached to this word.
きょう室に入ってください。
Come into the classroom, please.
このゲーム、むずかしすぎるよ。このめんで、１５６９号室まで行くには、どうがんばってもじかんが足りないんだ。
This game is too difficult. I never have enough time to get to room number 1569 in this stage no matter how hard I try.
保健室で眠っていました。
I was sleeping in the school infirmary.