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).
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.
I knocked on the president's office.
Is there a vacant room today?
The woman's corpse was in one room of this hotel.