Well, without more context, it's hard to say precisely. 'King zero novel' could be about a king who is considered the 'zero' or outcast in a line of royalty. It could explore his journey to prove himself, facing various challenges within the political and social structure of the fictional world in which the novel is set. It might also have some sort of symbolic meaning related to the number zero, like representing a new beginning or a lack of something that the king must overcome.
Since I don't have prior knowledge of a 'king zero novel', it could be a creative and experimental work. It might be a story that defies traditional ideas of kingship. For example, the 'zero' could imply that the king has no traditional power or status at the start. The novel could then be about his growth, his relationships with his subjects, and how he transforms from this 'zero' state into a respected or feared leader. It could also incorporate elements of magic or fantasy, where the concept of 'zero' has some magical connotation within the story's universe.