This signal has several meaning, but mostly is used by the Referee to indicate that there has been an undue delay, or that the 25-second clock has run out.
May also be used against the defense if they are not ready following a timeout and the offense are ready to snap the ball. Similarly against the defense when they attempt to simulate the cadence of the quarterback.
Penalty5 yards from the previous spot.
Both hands start at the waist and are brought across the chest in an unhurried motion.
Finally point to the offending team by stretching an arm out from the shoulder to the horizontal.