This is a contrived picture of a ballet step called an attitude turn. For this move the dancer needs to go from a position where she has her feet on the floor and knees bent to pushing up and lifting her leg in a 90 angle. In order to come up the dance pushes down into the ground, because of Newton's Third Law we know that for every action there is an equal and opposite reaction, that means that the floor also pushes the dancer up. Notice the arms of the dancer, one of her arms go up distributing her weight closer to the axis of rotation. That redistribution of weight reduces the rotational inertia and therefore increases rotational velocity, since the two are inversely proportional. The dancer's other arm is held beside her body and that helps her maintain her balance. The last thing the dancer wants is to have a torque in any direction, and since the leg needs to be held away from her body a torque is bound to occur, but the arms stand in a way to create a torque in the opposite way and therefore stops the dance from unbalancing as fast as she would have if her arms were simply by her side.