The word choice is the way that the author chooses to arrange and show expression with their words for sake of enhancing the story. This could for example mean using figurative language, or explaining everything in full detail so everyone can really understand the point that they were trying to get across.
The bunk house is described as a very uncomfortable, tight living quarters. The description shows that the men who live there are very poor and their lives were most likely disrupted by the Great Depression.
