It means someone who is confused. It;s orogns date back to an early dice game. The original game was called To Set On Cinque And Sice which were thought the riskiest numbers to throw for, and anyone who tried was probably confused. over time, the numbers have sifted to six and seven, and one theory is that those numbers add up to thirteen, which has always been considered unlucky. Through time, the phrase has settled into "all at sixes and sevens" meaning to be confused or muddled.