Learning → Categories & Tags has two tabs.
Category fields: Name, Slug, Parent and Description. The system Uncategorized category has a locked slug and cannot be deleted. Deleting a category moves the courses that were only in it to Uncategorized, so a course is never in none. A course can have any number of categories and tags.
There are no category pages: the public catalogue filters by ?cat=<slug>. A category grants no access and changes no price (a membership plan can be limited to a category, which is a separate setting). The lists have no search or paging and hold up to 2,000. Delete is immediate and has no Trash; the screen shows write buttons to anyone who can open it.