The head of a static liquid gives an idea about the pressure caused by the level of liquid and the potential energy due to the height of the liquid above the datum line.
Thus the hydraulic head is caused by two factor. The static pressure and the potential energy of the liquid above the datum line.
However, it is important to note that the head is not energy. It is a way of describing the static pressure and the potential energy.
Head is an important parameter in the design and discussion.