(figuratively) To be aware of one's position.

(informal) To understand one's situation, how to act in that situation, and the results of those actions.

Alternative form of better the devil you know than the devil you don't know

Synonym of know what one is about

Alternative form of know B from a battledore

(archaic, often in the negative) To know anything at all; to have the most basic common sense or intelligence.

To be confused about how to handle a situation.

(idiomatic) To possess confidential and incriminating information about a person's or organization's misdeeds or other secrets.

(colloquial) you have chosen the wrong person / (colloquial, literally) you are good at picking people or things

A rhetorical question asked to show that the person asking it neither knows the answer nor would be able to know it.