View Source

In the "Group Analysis\by Name" view, the black columns identify the

total number of direct and resolved members (Member count)
total number of direct and resolved ACL relevant members (ACL count)
total number of direct and resolved Mail relevant members (Mail count)
total number of direct and resolved unknown members (Unknown count)

SecurityInsider > Understanding the "Groups By Name" Columns > Groups Columns 1.png

The gray columns identify the

number of direct unknown entries only (# Unknown)
number of direct group entries only (# Groups)
number of direct person entries only (# Persons)
number of direct server entries only (# Servers)

Sorting by "# Unknown" (direct unknown entries) helps you to easily spot which groups directly contain unknown entries. Resolving such direct unknown entries will naturally also resolve unknown entries in any super-groups that nest groups with direct unknown entries.

Note that the Description column will only contain values ...

... if you choose to synchronize at least the ListDescription field from public addressbook group documents in SecurityInsider configuration:

SecurityInsider > Understanding the "Groups By Name" Columns > Groups Columns 3.png