Many novels consist of dialog - and the other part, the part that is not dialog. What do you call the part of a novel that is not dialog?
I think the most general term is narrative:
1 A spoken or written account of connected events; a story.
‘a gripping narrative’
1.1 [mass noun] The narrated part of a literary work, as distinct from dialogue.
‘the dialogue and the narrative suffer from awkward syntax’
Narrative includes exposition, which describes events that take place, and description, which describes people and places.
In a play this sort of material would usually be called stage directions, which might convey your intended meaning, depending on the audience.