Shows, how many days passed on average between visits.

CalculationURM - Customer Profile Days since First Contact / URM - Customer Profile Visits * 100                                                            

A user made 10 visits. The first visit was 100 days ago.
The value for "URM - Customer Profile Visit Frequency Avg. (Days)" is 10.

Note that the use of this metric over time is usually not useful, as there is no time reference.