Content-Group statistics are available in the Content reports that offer Content Grouping as a primary dimension.
You can also use a Content Group as a dimension in custom reports.
The names that you define appear as options you can select from the Primary Dimension > Content Grouping menu in your reports:
(not set) is the collection of pages that are not assigned to any group.
Click one of the group names to see statistics for the individual pages in that group.
Unique Views metric
The Unique Views count for a given content group represents the number of sessions in which a page in that group was viewed one or more times.
This metric does not include multiple views of pages within the same group within a single session. For example, if a user comes to a web page on your site and in the course of the same session returns to that page 10 times, this would count as 10 Pageviews, but only 1 Unique View.
When you have a row identified as (not set), the value for that row is always 0. When Analytics calculates metrics for Content Groups, those calculations are based on the index number identified on the page or screen. When a page or screen does not include an index number, no calculation is made, and it is included in (not set).