The whole sentence is "It's like a bird that has eaten all its food and throws it into the forest, leaving a vast white land that is really clean."

It means that people compete for fame and wealth until the end, just like the birds have eaten up all the food and scattered into the forest, leaving only an empty vast land with nothing, which refers to all the prosperity in the end. All returned to emptiness, leaving nothing behind like the vast white wilderness. It is a metaphor that the characters in the book, the glorious and prosperous life, and the illustrious family glory all disappeared in the end. Extended information

"A Dream of Red Mansions" comprehensively and profoundly reflects the characteristics of the era of prosperity and decline of feudal society. What it describes is not a love story with "flowers and candles in the bridal chamber and titles on the gold medal list"; it describes the love and marriage tragedy between feudal aristocratic young men Jia Baoyu, Lin Daiyu and Xue Baochai.

The great social significance of the novel is that it does not describe this love tragedy in isolation, but takes this love and marriage tragedy as the center and writes about the representative characters of Jia, Wang, Shi and Xue at that time. The rise and fall of the four major families, with the Jia family as the center, reveals all the darkness and evil in the late feudal society.

With its insurmountable internal contradictions, it makes a powerful criticism of the decadent feudal ruling class and the feudal system that is about to collapse, making readers have a premonition that it will inevitably lead to destruction. At the same time, the novel also expresses new hazy ideals by praising aristocratic rebels.

"A Dream of Red Mansions" exposes all kinds of darkness and evil in the late feudal society, as well as its insurmountable internal contradictions. It makes a powerful criticism of the decadent feudal ruling class and the impending collapse of the feudal system, making readers have a premonition. To the point that it will inevitably lead to destruction; at the same time, the novel also expresses new hazy ideals by praising aristocratic rebels.

In the history of Chinese literature, there is no work that can describe the tragedy of love as exciting and powerful as "A Dream of Red Mansions"; nor is there any work that can describe the social roots of the tragedy of love like it does. It is revealed so comprehensively and profoundly that it makes the most profound and powerful criticism of feudal society.

Baidu Encyclopedia-Dream of Red Mansions