What is meant by the term 'copyright'?

It means that the photograph has been protected by copyright laws and any use of the photo must be done with the permission of the copyright holder.

There are 2 aspects to the copyright. An unregistered copyright protects the owner of the image and legally allows them up to $300 in claims against anyone copying the image illegally. A registered copyright must be filed through the government and allows greater claims against the infringer