This sentence expresses people's complicated feelings. Some knots may always exist and be hard to let go, and past words and emotional experiences may also become burdens and troubles in their hearts. At the same time, how to express these feelings and how to tell others may be as illusory and elusive as fate in a dream.
So the meaning of this sentence is that people's deep feelings and knots are often difficult to release and express, and this kind of emotion may be as illusory and elusive as fate in a dream.