Dreaming of the void (an abstract idea) indicates the state that you are in mentally. It expresses the lack of motivation at the time to do things. You should try to fill this void with new projects, objectives, and hopes. If you dream of a room, a box, a house, or empty spaces, it expresses an emotional deficiency. According to Freud, the origin of these feelings is in one’s own repression. The things you propose to do in moments like this will be futile.