The speaker has an unwelcome visitor: a snake that has settled in the middle of their garden. At first they plead for help, then try asking the snake to leave politely, but it hisses back and seems to resent them. The speaker grows more frustrated, pointing out that the snake scares people, eats the leaves, and blocks the growing flowers.
Then the poem turns. The snake leaves, and all that remains is a "hollow imprint" in the grass. Instead of relief, the speaker cries, and a flower grows as the tears fall. The last lines flip the earlier wish: now they wish the snake hadn't gone.
The snake may stand for something else, such as a difficult person, a painful feeling, or a habit, though the poem never says. Whatever it is, the mood moves from annoyance and anxiety to quiet sadness. The poem suggests that even something troublesome can leave an emptiness behind when it's gone.