Hi Cat,
To answer your question here:
The User Visits report shows the total number of User Visits in the forum for the selected time period (today, yesterday, last 7 days, month, etc).
Specifically, a User Visit is counted anytime a unique logged in user visits the site, up to once per day.
For example, if a user visited a site every day within a week, Discourse would count that as 7 user visits. This is why it’s possible to have more user visits in a month than your site has total users.
If you’re interested, you can also view the Ruby Code for this report here as well: discourse/app/models/concerns/reports/visits.rb
I hope this helps! 