Drives are devices used to store data. Most computers have at least two drives : a hard drive C:\ and a floppy drive. The hard drive is typically designated the C:\ drive and the floppy derive is typically designated the A:\ drive. If you have an additional floppy drive, it it typically designated the B:\ drive.
There are also network drives on your computer, depending on authorization and rights of each user. This drives will typically be labelled F:\or H:\or G:\.