The harpist sits with the harp between the legs and tilts the instrument onto the right shoulder. He/She plays the strings with the right hand from the right side and with the left hand from the left side.
The right hand usually plays notes in the higher register and the left hand notes in the lower register. However, the strings in the middle and high register can easily be played by either hand. The strings in the low register, on the other hand, can only be played by the left hand since the harp rests on the right shoulder and thus limits the reach of the right hand.
Reach of the hands.