A garlic peeler is a kitchen tool intended to speed and ease the process of peeling the papery skin off from cloves of garlic.
A common design is that of a ridged rubber tube. You put an unpeeled garlic clove inside, press down with the palm of your hand on the tube, and roll it. The skin on the clove is meant to be rubbed right off by the friction of the rolling process.
These designs are usually dishwasher safe. Some silicone ones are made in the shape of a bulb of garlic, and work with the same press and roll technique.
There are also electric ones. You put several unpeeled cloves at once into the machine. When you press a button, they get agitated and rub up against a grate which rubs off the skin. Some users have reported that clean-up of such machines can be fiddly, and that bits of skin can get left on the cloves.
Some people say that they find the garlic peelers they have tried so far don’t work, are fiddly to use and just prolong the job of peeling cloves of garlic.
To remove the skin from a garlic clove without a garlic peeler: take a whole, unpeeled clove of garlic and lay it on a cutting board. Take a broad-bladed knife or cleaver, lay it sideways on the clove and pound it once with your fist. The skin will easily pull away.