It can be used in the oven or on a covered BBQ grill.
There are many differently designed devices and stands. Most are made of metal but there are some made from ceramic.
A Vertical Chicken Roaster lets you fit more chickens in the oven at the same time. Some have a bowl at the bottom that collects the drippings that come off, and stops them from splattering around in the oven.
When purchasing one, see if it’s dishwasher safe if that’s a priority for you — not all are.
To use one, season the insides of the chicken first according to taste, then poke the neck cavity of the bird down onto it. If your model doesn’t have a dish on it, then you definitely need to put it on something to catch the juices. But even if it does have a dripping catcher, putting it on a roasting pan or cookie sheet makes it easier to get out of the oven afterward.
Some people baste the chicken during cooking, but that seems to defeat the whole point of roasting vertically to keep all fat off the bird.
Chicken can get stuck to the roaster, making it hard to get it off without spoiling the presentation. You may need two people to get it all unseparated. If you’re on your own, lay it flat on a board or plate, use a fork to hold the bird, and use another fork to pull the stand out of it. Spraying cooking spray on the stand before putting the bird on it may help.