What is meant by pressure energy ?

Pressure energy refers to the energy of the liquid due to its pressure.  As the pressure of a fluid increases, the pressure on the molecules of the fluid causes some energy to be stored.

Pressure energy is defined as the ratio of the pressure difference to the specific weight of the liquid.  The unit of pressure energy is Joules/kg

Pressure Energy along with the potential energy and the kinetic energy constitutes the Total Energy of a liquid.