Apple's 'BootCamp' scheme is a software system that allows Mac OS-based computers to dual-boot to other operating systems, including Windows. That is, when the system starts up, one has the option of running either the Mac OS, or another operating system such as Windows or Linux. This is very different from running Windows in a virtual machine. With a virtual machine, the host OS boots, and then, one starts a hypervisor program (like VMWare Player or Virtual Box) and then, additionally, the guest OS boots inside the hypervisor program, and runs at the same time as the host OS. With BootCamp, you choose, and only run one operating system at a time. This allows Windows (or Linux) to have sole access to the computer's RAM and other hardware, at the expense of dividing the hard drive into separate partitions for each OS, and having to reboot to switch between the OS choices. It's recommended for running Windows on older Macs when system performance is important.
If your computer has been setup with BootCamp, and you need to know how to switch between operating systems, see