How does Steinbeck use language and objects to present Crooks?

Crooks' possessions tell us a lot about him. In Chapter 4, we see the inside of his room, which he has all to himself because he is a permanent fixture of the farm, as opposed to the rest, most of whom are itinerant workers. This is clear also because he has plenty of possessions since he doesn't have to carry everything he owns on his back, like those of the drifters who have to roam from town to town finding work. 

From the mending tools and broken harnesses by his window, we can see that he's good with his hands; he repairs various stable gear. 

He has "a range of medicine bottles, both for himself and for the horses," which tells us that he not only needs various medications, but can afford them, suggesting he makes decent money. Also, he appears to be the farm veterinarian to some extent. He has the cans of saddle soap, as well, meaning he maintains barn materials in addition to repairing them. The drippy can of tar is also for repairing things, like the roof. 

Unlike most of the others, he has several pairs of shoes, used for different tasks. He is something of a jack-of-all-trades, then. He has an alarm clock as well, which suggests that he keeps his own schedule and helps the stable hands keep theirs. He also has a single-barreled shotgun; despite being a black man, he is trusted with this weapon and probably uses it to shoot varmints. 

He also has glasses and books. Not just any books, either; he has a dictionary and a much-read copy of the California civil code for 1905. This is not an easy read, and probably not a particularly pleasurable one. Crooks, then, is an educated man.  

He is clean. Despite the various tools and objects around, he keeps the room clean and well-swept. 

Finally, he keeps his distance and expects--or even requires--that everyone else keep theirs. This is probably because he is a black man and knows most of the men would not accept him as one of them, so he responds by keeping his own company, rejecting them before they can reject him. This suggests that he is lonely, not by choice so much as necessity.