What does can't mean?
can't
Definition
Marks a possibility as incompatible with available clues: the speaker concludes that a situation cannot be true or an event cannot have happened. Expresses deduction, not inability or prohibition.
Example sentences
She can't have gone home; her car keys are still here.
That can't be the right address; this building has only two floors.
That can't be the right address; this building has only two floors.
He can't have taken the train; the line was closed all day.