The current BIOS version can be displayed in Windows via the command prompt or system information:

BIOS version via the command prompt

The BIOS version can be read out in the command prompt with the following command: "wmic bios get smbiosbiosversion".

C:\WINDOWS\system32>wmic bios get smbiosbiosversion
SMBIOSBIOSVersion
L77 Ver. 01.50

Alternatively: System information msinfo32

The system information shows the version as well as the date: BIOS -version/date

BIOS mode: Legacy (BIOS)

Whether Legacy or UEFI is used as boot mode can be found in the system information under "BIOS mode":

UEFI

or Legacy:

See also: Change Windows 10 BIOS (Legacy) to UEFI Boot