skin as a countable noun example
The form "skins" is often used to refer to pelts of animals in the context of hunting.
There are quite a number of other cases as well when this form is appropriate. For example, the term is used to describe thin strips taken from the outside layer of something, like a vegetable, as in "onion skins". Stuffed "baked potato skins" are a popular snack or meal in North America.
For many other examples, see https://www.wordhippo.com/what-is/another-word-for/skins.html.
Hope that's helpful.