Bare-metal in this context means that you have physical hardware and you're responsible for making sure the system can boot and do the stuff you want, as opposed to what you'd have with a service like Amazon's EC2, where you're given a set of apps to configure and execute a virtual machine image. The distinction is made because the former scenario requires extra work for initial configuration (in terms of OS installation and physical networking and such) and you have the burden of setting up automation to handle scenarios where your OS installation is hosed, and much more.