The topics you see listed on this report are the words or phrases that have been derived from the content in your newsletter that have been most engaged with. You can view the most popular or trending topics within your audience for any date range. These topics can greatly inform you on what your audience is most interested in and help inform your upcoming newsletters in the way of content selection.
Another place you can view Topics on the dashboard is on the landing page when you log in. It will look like this: