Light is a kind of energy (power).
There are different kinds of light. We human beings can see only some kinds of light. The light we can see is called "visible light".
"Visible" means that our eyes can take it in and figure out quickly what it is.
For instance, it we turn our heads towards a tree, our eyes take in the colour of it, the shape of it, and where it is growing. We know pretty quickly that it is a tree (and not a tractor), because our eyes tell us.
The sun gives off visible light.
An electric bulb gives off visible light.
This visible light bounces off things (like the tree) and then goes into our eyes.
Our eyes then take the visible light and make us able to see.
Try looking for something in a dark room. Can you see it?
Now switch on the light. Can you see what you're looking for now?
The light from the electric bulb bounces off things and so you can see them.