Directional lighting is used to be similar to sun light. This light will cast shadows parallel to the object the light is hitting. This makes it the ideal sun light.
Point lights emit light like light bulbs. Point lights emit light equally in all directions from a single point. You can use point lights as light bulbs in a level.
A spot light emits light in a single direction in a cone shape. You can use spot lights as stage lights on a stage level in a game.
These three different types of lighting can be used to create different effects in games. Brightly lit games can be exciting and darkly lit games can be scary and intense. Using just light alone can set the theme of a video game level.