does anyone know the definition of conservation of energy is?? i?

If you don't mean the first law of thermodynamics then what do you mean?

If you mean conserving energy such as turning out the light behind you when you leave an empty room, that's a different matter but you need to be more specific.

In general use, it means we turn off devices that consume the energy we generate from fossil fuels, from nuclear or other means. We 'conserve' by using less.

In scientific terms, it means that for every action there is an equal and opposite reaction. Energy expended must be generated by action elsewhere.