Areas are places where data points (fields) can be collected, these fields can then be used in KPI calculations.
Areas keep these fields organized in P1 and make it easier to identify where a specific data point (field) is located and making it easier for Administration to control access to specific parts of the P1 site.
After clicking on the "New Area" link, there is the option to either create a completely new field using the blank template that automatically pops up, or to select an existing area from the left hand accordion bar to edit it.