PC people - what does BIOS lock mean?

[pinkoos]

Looking at a used Lenovo laptop and the seller has listed it as having a "BIOS lock" but that "does not affect performance at all"

What does that mean?

Is a BIOS lock similar to the existence of a firmware password and not knowing what it is on the Mac side of things?

Curious if a BIOS locked PC is still useable, software upgradeable, able to log in to Windows, etc.

Thanks