Authentication types allow your users to login using different logins from various services, such as Facebook. You can view your available authentication types here.
Please note that the core concrete5 authentication type "Standard" cannot be disabled. However it can be moved down in the list to not appear as first authentication type during login.
If you click one of the entries, you will be able to configure the authentication types. Many 3rd party authentication types will require things like API Keys, App ID's, etc. to function properly. Reference the documentation from the authentication provider you'd like to use for more information.