A roll-up of content in the Behavior reports that groups several pages or screens together to better reflect the structure of your site or app. Content groupings allow you to view and compare aggregated metrics by content group name, as well as individual URL, page title, or screen name.
Content Grouping lets you group content into a logical structure that reflects how you think about your site or app, and then view and compare aggregated metrics by group name in addition to being able to drill down to the individual URL, page title, or screen name. For example, you can see the aggregated number of pageviews for all pages in a group like Men/Shirts, and then drill in to see each URL or page title.