Modern enterprise grade websites make use of something called a CDN, or Content Delivery Network. Your site uses https://www.cloudflare.com/ as the CDN provider.
This is basically a global array of servers across the US and the globe.
"Copies" of your site are uploaded to those servers at regular intervals. These are referred to as "caches". The net effect is that when your user requests a page on your site, the request only has to go to the nearest available server, rather than sending the request all the way to a single server location in one spot on the planet and back.
It's primary purpose is to reduce load times of your content and ensure that no matter where someone is, your website is always easy to reach.
Now, when you make a change while logged into the site, you are making a change to the primary server. Those changes "roll out" to the content delivery network as the "cache" (copies) expire.
Most changes you make automatically delete the cache to push an update out.
However, if you experience a scenario where a change you made is not visible when you are not logged in, you may need to purge the page cache.
Whenever you are logged into the site, if you want to "push" a change immediately to the CDN, you can "purge" (delete) the copies that exist on all the servers worldwide, so that they fetch a new version.
To do so, simply navigate to the page in question (like your homepage) and use the tools icon to select "Purge cache for this page".