The meaning of this poem is that when I was writing, I mistakenly used vinegar as ink. As I was writing, I smelled a sour smell when I was about to finish writing, and I realized that I had used vinegar as ink. After I wrote it, the paper was filled with the sour smell of vinegar.
This poem describes a person who made a mistake when writing. He mistakenly used vinegar that should be used for painting as ink, causing the paper to be full of sour smell. This metaphor describes a feeling of extreme helplessness and regret, like a person who is pursuing a goal but fails to achieve the expected results due to negligence.