He's actually "rotating" the entire aircraft around its horizontal axis (imagine an axle running from wing tip to wing tip) to an attitude (nose up in relation to the ground) that will cause the aircraft to fly. This occurs when the aircraft has reached a predetermined speed. The speed is different for each take-off since it's influenced by a number of factors, such as aircraft weight and air temperature. The "rotation" is caused by pulling the control yoke backwards (aft) which, through various mechanical, electrical or hydraulic devices forces the horizontal stablizer on the tail of the aircraft to move in an upward direction. This movement causes the tail to go the opposite direction (down) with the end results of raising the nose of the aircraft. The actual benefit is that the angle of the wing is then raised to a point where flight occurs. This angle is termed "angle of attack".... More than you really wanted to know, I'm sure...