Since this is a free kick, no kicking team player can touch the ball until it has either touched the ground or a receiving team player. The foul is kick-catching interference. The penalty is 15 yards from the spot of the foul (known as the spot of the "awarded fair catch") or 15 yards from the previous spot and rekick, or the receiving team can decline the foul and take the result of the play (depending on how the play ended, what's more advantageous).
This is different than a scrimmage kick (punt, FG, etc.) where if there is no receiving team player in position to catch the ball, a kicking team player can touch a kick in flight.