This has two meanings, one more general, one more specific. A description may also represent a scene.
Some people think that what is going on inside our heads is pictures or descriptions.
The important thing is that internal representations are not observable. In that sense they are like physicists' quarks, the unobservable things I was describing in lecture. I visualise them in my mind. Homuncular theories, theories that are based on what goes on in my mind, never explain what it is to BE a mind, to BE an observer. They always assume an unexplained observer.