This sentence came from the classic Chinese novel,"Dream of the Red Chamber". It meant that Jia Baoyu had been troubled by some demons to a very serious extent while he was wandering in the Great Void. Jia Baoyu's Wandering in the Great Void was a plot in the novel. It referred to Jia Baoyu leaving the real world for some reason and coming to a space called the Great Void. In this space, people could experience different dimensions and realms, while Jia Baoyu gradually improved his cultivation and realm through continuous cultivation and experience. Evil Demons referred to some improper magic power or monsters that might cause harm to humans. In the novel, Jia Baoyu was troubled by some evil spirits, which meant that he had been affected by these evil forces and had reached a very dangerous level. The meaning of this sentence was that Jia Baoyu had been affected by some evil forces in the Great Void and had reached a very serious level. He needed to take effective measures to protect himself.