This is a custom metric or formula.
Unfortunately, we cannot provide further information on the calculation of the figure in the Support Center, as each custom metric and custom formula is configured in your Webtrekk system.
Click in the main menu on "Custom Figures > Custom Metrics" or "Custom Figures > Custom Formulas" to get a list of all custom figures. By clicking on the corresponding figure you can see how it is calculated.
Please note that you need the rights to be set in the user management to see the menu item on custom figures. If you don't see it, please contact your administrator.