Yes it is true that the potential energy can be converted into kinetic energy and kinetic energy can be converted back into potential energy.
Explanation:
The kinetic energy can be converted into the potential energy and similarly the potential energy can then be back converted into the kinetic energy too. This happens according to the law of conservation of energy. The law specifies that the energy remains constant but the form of energy is interchangeable.
Clearly speaking, the energy can be converted into any form of energy for numerous times but the total amount of energy remains the same in a closed system. For example, the energy conversion can be observed in the trajectory of the ball thrown upwards.