From working with servers and PCs, you are familiar with common components like CPU, RAM, Disk, network, and so on.
When using server virtualization, each guest operating system will have its own virtual components such as the virtual CPU, virtual memory (RAM), virtual disk, virtual network, and so on.
Inside the guest operating system, the OS will see these devices as physical devices and you may or may not have the vendor’s virtualization driver loaded for that device. These virtual devices are configured in the virtual guest configuration for that VM, in the management interface for your virtualization software.