There is an explanation under "About the author" section :

This "author" was created to segregate those items which have ISBNs but are not actually books. For more information, see the manual and/or start a thread in the Librarians Group.

When an item which is not a book is imported via ISBN into Goodreads, it does no good to delete it: the item will only be re-imported as long as it remains on the feeder site. (Often these are book-related items which are assigned ISBNs by book publishers so that they can be tracked through their book systems.)