Focusing on the symbolism of the setting, it is the literal, unfinished fence that stands out as the most significant element of the setting.
The fence represents different things for different characters. Troy has been engaged in a life-long sense of battle against his limitations, in sports, in his profession, and in prison. He feels that these limitations have been pressed upon him by an unfair world.
Troy also sees white America having a fence that keeps blacks contained, apart from the good life that whites enjoy. It is the fence that kept him from realizing his dreams and the fence that makes blacks garbage collectors while whites advance to better positions such as driver.
Rose looks at the fence as a way to protect and define he place in the world and her family.
Rose thinks the partially built fence around the house will keep her loved ones safe inside.
Importantly, the fence in the actual yard is unfinished and it is Troy building it. He attempts to get his son's help, but ultimately finishes the fence himself. This symbolism resonates with the notion that Troy has been building up the idea of his own limitations.