Answer:
It illustrates how the grief is like a backpack because the speaker carried it with him everywhere.
Step-by-step explanation:
Parallelism is the figure of language that describes ideas or expressions that have equivalent meanings, similar structure and that we can establish some kind of comparison between them.
In this case, the author used the parallelism to make a comparison between a backpack and his mourning, this comparison was made as a way for the author to express that his mourning accompanies him wherever he goes, similar to a backpack stuck on his back