The Law of Conservation of Energy in English
The Law of Conservation of Energy says that when zero total external WORK is done on a system or done by a system, the total ENERGY of the system will not change.
The kinds of energy a system contains might change, but the total of all of the energy in the system will not change if zero total external work is done on or by the system.
The kinds of energy a system contains might change, but the total of all of the energy in the system will not change if zero total external work is done on or by the system.