With the option
hypertexnames hyperref uses the corresponding counter in addition to the link type to construct the link name. Imagine, you have two chapters and one section in each chapter plus one table. The link names would be:
hypertexnames it's just counting upwards, using the
\Hy@linkcounter instead of the corresponding chapter resp. section counter. It's similar for other objects and links to them.
hypertexnames you could guess the link name, if you would like to use it for referencing, from the corresponding counter value instead of a shared counter.
hypertexnames in hyperref.sty gives further information, for instance in the definition of the command
\hyper@makecurrent. But you could also take a quick look into the .aux, .toc, .lot etc. files to notice the different kind of link names.