This sentence refers to the story of the characters in "A Dream of Red Mansions", which is a metaphor for the impermanence of the world and that all good things will eventually fade away.
In this sentence, "A Dream of Red Mansions" refers to the life spent by the protagonist Jia Baoyu in the Red Mansion, while "Eventually becomes empty" means that this experience eventually became illusory.
Similarly, "Smoke willows drunken by the spring breeze" is also a metaphor, implying the short-lived spring and beautiful scenes. People at that time were also intoxicated in it as if they were drunk, but as time went by, these beautiful scenes Things eventually pass away. This sentence aims to warn people to cherish everything in front of them, seize and enjoy the beautiful moments in life in time.