The author of this poem is Gao Kegong, and it comes from Gao Kegong's work "Viewing the Sea with Joy".
The original text of this poem: The sunset is overflowing with color and the clouds are shining, and the green mountains are sweet all year round. I am never idle as long as the mountains are green, I am busy all my life. After decades of ups and downs, the loess is buried in my chest in the blink of an eye. I laugh at the green mountains, my face remains unchanged, and the green mountains laugh at my old age.
The phrase "The green mountains laugh at me" in the sentence "The green hills laugh at me" is an anthropomorphic expression. Qingshan cannot really smile, but the poet uses this rhetorical technique to compare Qingshan with himself, implying that he is old and aging. The word "old age" here expresses the poet's understanding of his own age.