Directional light is a type of light very different from the (point of light), the directional light illuminates the whole scenario, if a material is established that is applied a directional light that in this case are 6 spheres, all the spheres are distant or separated, they will have light despite being far away since it is a directional light and does not establish a (point of light)
In the directional light it does not matter if you change the parameter of the positions of the light (x, y, z), only the parameters of the rotation (rotationX, rotationY, rotationZ) matter. In the directional light you can modify the speculation,diffuse, color of light and environmental color.
If we want an object like this, a model with shadows, the directional light comes with a box (castshandows). Once the objects are marked, they will be affected with shadows (depends on the rotation of the light), if the rotation is to the right, the shadows will look to the right, the shadows have a parameter to which you can set the distance of the shadow, the less distanced the shadows are, the shadows will be clearer from a distant point of view, but the less distanced is the Shadows will be very clear, but from a lesser point of view, for example, the shadows of the other objects will not be seen with the camera so far. with the ambient color of the light you can change the color of the shadows and it is recommended that the distance of the light is between 0.48 if you want the shadows to be seen when the camera is away from the objects