WHAT IT DOES
A wallpaper steamer boils water continuously to release steam through a square nozzle. It helps you remove wallpaper by softening the glue or wallpaper paste.
There are simpler techniques to wet the wallpaper such as using a hand sprayer or a sponge (see video here: https://youtu.be/2j2dzp1JwDs?t=5), but the steamer is particularly useful if the wallpaper has been painted over or if it was applied a very long time ago. Here is a good read to help you decide what removal technique to go for: https://www.dummies.com/home-garden/walls-ceilings/getting-to-know-wallpaper-removal-techniques/