This panel gives you an overview of how many pages have been optimized by NitroPack.
You also see how long ago a cached page has been purged.
Clicking the large number gives you a breakdown of the number of cached pages for every page type - mobile, tablet, and desktop:
Clicking this button will delete all cached pages. As a result, cached content won't be served on the next page refresh. Updated content will be seen immediately but with a slight loading delay until NitroPack performs new optimizations.
In most cases, you won't need to use this button. NitroPack automatically invalidates and purges cache, depending on your actions in the WordPress back end.
However, if you changed something on your site and want to show it immediately to visitors, you can use the Purge Cache button.