The homepage for unregistered or not-logged in users, is usually the first thing users see when they enter the site.
You can change the Sphere image of the home page and the welcome text.
Also, it is possible to add 2 call-to-action buttons of your choise. By default the buttons are short-cuts to the login or register page. But you can also use them to point out interesting news, documents etc.
Make these changes via the dashboard in the Appearance section Customize home page. You can also paste this link behind the site url: /admin/structure/block/block-content
AN Homepage hero Block
The block description is mandatory and pre-filled, but is just for administration, it is not shown in places where normal members can see it.
Call to action buttons.
Change them by entering the url you want to button to point to (if it is an internal link, it is better to only enter the part of the url that comes after the .com)
Next step is to fill in the text that should be reflected in the button (the link text field).
Sphere image and welcome text
Further down the page you can change the image and the text.
Save it: and there is your customized Homepage! (don't forget that you have to logg out to see the result, as this block is only shown for non-logged in users)