The next sentence is that fish sink and geese fall.

Fish sink and geese fall, birds frighten the moon and flowers tremble.

A heavy fish and a wild goose close the moon and feel ashamed of flowers here refers to four characters, which are used as pronouns here.

A heavy fish refers to a stone, a wild goose refers to Wang Zhaojun, a closed moon refers to The Story Of Diu Sim, and a shy flower refers to it.

Fish sink and geese fall, birds frighten the moon and flowers tremble.

It implies that beautiful people make birds scream and flowers tremble with anxiety.

This sentence can be used to describe the beauty of other women.