This is a site maintenance category for images. It lists all (known) images which do not have the proper copyright information on them. Images listed here should have their copyright information corrected so that they can be removed from here. Ideally, this category will be empty.
You can help out by looking at the images listed and figuring out where they came from then adding the proper information. If the image is not used anywhere then you can tag the image with Template:Delete instead.