An extra question used for setting up an account somewhere in case you forget your password.
However rather than adding extra security like they think they do, they make your account easier to hack because whilst you may have a great unguessable password, these questions are often easy for someone to guess or even know the answer to.
A sensible person would not give an accurate answer to one of these questions and would in fact have an answer that is as hard to guess as a password.
As an extra security question, Brooklyn Beckham, what is your mother's maiden name?:
Wouldn't be Adams by any chance?