By default, when accessing your website simply by using the domain name (www.example.com), your website will look for an index.php or index.html file in the root folder (/public_html/).
If those files are missing, you will only see an "Index of /" page instead similar to this:
In order to fix it, you have a few options:
Disable directory listing from your control panel. Navigate to the Folder Index Manager page. On the directory field, enter the public_html folder. On indexing type, choose No index and click Add:
You can also create an empty index.html or index.php file if you don't want any content to be displayed (but want to disable the list of directories). This can be done using File Manager:
The best way to resolve this would be to build a website!