Hello. You did not inform the poem to which this question refers, which makes it impossible to formulate a question exactly. However, I will try to help you in the best possible way.
The simile is a figure of speech that establishes the comparison between two elements that have different contests, but that can, subjectively, promote a link between both. The idea of the simile is to create a symbolism, a different meaning, that in a subjunctive way shows a characteristic, that promotes a strong meaning.