Luminous energy is what makes things bright and shiny in the dark. Imagine you are holding a flashlight in a dark room. The flashlight uses energy from its batteries to create light so you can see things. The more energy it has, the brighter the light will be.
Now, let's say you turn off the flashlight and it's completely dark. Suddenly, someone turns on a lamp in the corner. The lamp is using energy from electricity to create light, just like the flashlight used energy from its batteries.
The thing is, not all kinds of energy can make things luminous. For example, when you rub your hands together, you create energy in the form of heat. But that energy doesn't make things bright - it just makes your hands warm.
Luminous energy comes from things that give off light, like bulbs, flames, or even glowing objects like stars. When these things are giving off light, they are using luminous energy.
So, to sum it up, luminous energy is what makes things bright and shiny in the dark. It comes from things that give off light, like bulbs and flames, and it's different from other kinds of energy like heat.