Page caching saves a static version of your pages so they load faster for visitors, since the server does not need to rebuild the page from scratch on every single visit.
Go to Dashboard > Marketing & SEO > SEO > Page Caching.
Turn this on if you do not update your website content very often. Faster page load speed is good for both customer experience and SEO ranking.
If you make changes to your website after enabling page caching, you need to run the caching process again for those changes to show. Otherwise visitors may keep seeing the old cached version of the page.