UEFI (Unified Extensible Firmware Interface) and BIOS (Basic Input Output) are two different types of computer (PC) firmware which provide an interface between the operating system and the underlying hardware of your computer. BIOS is an earlier firmware developed by IBM in 1975. Although legacy mode (BIOS) is still widely used at this moment, a new modern firmware has evolved which is called UEFI and it is developed by UEFI consortium (which includes 140 technology companies).
UEFI uses GUID (Guid Partitioning Table) while BIOS uses MBR (Master Boot Record) partitioning styles. When you ae installing an OS on your computer, ensure that you boot into the right mode. If you have a GUID partition, go for UEFI boot mode otherwise use BIOS.