In layman's terms, what's that involve, exactly?
An image is basically a snapshot of a Windows installation. Technician will install a fresh copy of Windows on a test PC and all required software and drivers. Some features are enabled, others disabled. Then final changes are made before taking an image of this installation, typically using tools like imagex or dism. The image is then stored on the server as a .WIM file.
Re-imaging means applying this file to the hard drive of many computers at once, so when they boot up they are ready to go. All the drivers, ticket software etc and user accounts created on the test PC exist and the computers are configured and usable.
This is done by booting the computers using a network boot option which loads and automated version of the normal Windows set up over an Ethernet cable and installs Windows automatically. This tool is called Windows Deployment Services and is available on all versions of Windows Server.
Sometimes a special script is written containing naming conventions. This way all the computers names can be looked up should they need to be, accessed remotely.