They skip the Out of Box Experience setup screens before your first logon. By skipping OOBE, you're responsible for applying all the settings that OOBE would have asked you about. Otherwise Windows provides the system defaults for settings like the hostname, default language, region, privacy settings, etc.
Before disabling User OOBE, you're required to create a primary user account in Unattended mode, or enable the built-in Administrator for logon. If you forget this step, then Windows won't allow you to logon normally.
Most of the first-time logon problems are from skipping OOBE, and not properly creating a primary user. Which is why NTLite beginners are recommended not to change OOBE, until they understand how to use the Add local user wizard to fill in the missing details.