I think these are very generic statistics determined by some sort of unknown logic:
The column after the Activity
is Pages/v
which I assume is "Pages Per Visit (average).
The low/medium/high activity titles are probably determined by the number of pages a visitor browses in one session. This is where the "unknown logic" comes in. These numbers likely mean that there were "xyz" visitors who visited more than high logic
pages, "rst" visitors who saw between low and high logic
and then "abc" visitors who went to fewer than low logic
.
In fact, I'm almost certain of that. If you look into the company or software that generates those statistics, perhaps they will provide information as to exactly what "High, Med, and Low" activities are.
Maybe beyond number of pages visited, it accounts for time spent on pages as well.