Simply saying, it will set the BIOS settings to default. It's similar to removing the board's CMOS battery. For more info, google for clear CMOS.
So if i mistakenly update a bios from my GPU or motherboad that causes an error or like a bios brick, I'll jsut press clear CMOS and it will return to normal but with a default settings? Ohh whwhen I google clear CMOS, this topic is in the top search ,