The purpose of pointers is something you will not fully realize until you actually need them for the first time. The example you provide is a situation where pointers are not needed, but can be used. It is really just to show how they work. A pointer is a way to remember where memory is without having to copy around everything it points to. Read this tutorial because it may give you a different view than the class book does:
http://www.cplusplus.com/doc/tutorial/pointers/
Example: If you have an array of game entities defined like this:
std::vector<Entity*> entities;
And you have a Camera class that can "track" a particular Entity:
class Camera
{
private:
Entity *mTarget; //Entity to track
public:
void setTarget(Entity *target) { mTarget = target; }
}
In this case, the only way for a Camera to refer to an Entity is by the use of pointers.
entities.push_back(new Entity());
Camera camera;
camera.setTarget(entities.front());
Now whenever the position of the Entity changes in your game world, the Camera will automatically have access to the latest position when it renders to the screen. If you had instead not used a pointer to the Entity and passed a copy, you would have an outdated position to render the Camera.