Complex sentence: An isentropic flow is a flow that is both adiabatic and reversible, that is no energy is added to the flow, and no energy losses occur due to friction or dissipative effects.
Split into simpler sentences: An isentropic flow is a flow that is both adiabatic and reversible. That is, no energy is added to the flow, and no energy losses occur due to friction or dissipative effects.