It's a roll easel. You use it to make multiples exposures of the same negative. Yes you need to insert a roll of photo paper and tape it to the spool on the other side. The easel will advance the paper when triggered. Depending on your gear, this can be automated. Some computerized enlargers will trigger the easel. But most of the time, the easel can be programmed to control the enlarger bulb. With that setup, you can automatically make as many prints as you want. Of course when you cover the window to insert another neg you can also make a variety of prints on one roll.
The roll needs to be developed in a machine. Developing a roll in a tray is fairly difficult I would say.