Example
For example for a retail clothing site, you might group content into men and women, then on each of these groups, we can create sub groups like T-shirts, jeans, outerwear and shoes.
Content grouping can be done by 3 ways:
1- By modifying the tracking code by each group you want to track.
2- By creating rules
3- By creating Regex (regular expression).
More information can be found here: https://support.google.com/analytics/answer/2853423?hl=en
After you have set up your content groups by using any of the above methods as listed above, you can see content groups as a primary dimension in your analytics dashboard.
Have a look at this video given below:
Also See:
Custom Variables in GA
Difference Between Clicks and Visits
Understanding Goal Flow in Google Analytics
Google Tag Manager
Multi Channel Funnel in Google Analytics
Regular Expressions on Google Analytics
Search Queries in Webmasters Tools