The following sentence actually employs three different kinds of figurative language:
The men noticed her firm buttocks like she had grapefruits in her hip pockets; the great rope of black hair swinging to her waist and unraveling in a wind like a plume; then her pugnacious breasts trying to bore holes in her shirt.
A simile is a figure of speech in which a person compares one thing to another using the word like or as. In the quotation above, the woman's buttocks are compared to grapefruits, using a simile, in order to emphasize how round and firm they look to the men. (We learn, later, that this woman's name is Janie Starks.)
A metaphor is a figure of speech in which a person compares one thing to another by simply saying that one thing is another; a metaphor does not use like or as. When the narrator describes the woman's great rope of black hair, the narrator compares a large braid of hair to a rope, emphasizing its thickness and strength in appearance. Then, the narrator says that the wind unravels that braid like a plume. This is another simile, comparing the braid of hair to a plume of bird feathers that is separated by the wind.
Finally, the narrator describes the woman's breasts as trying to bore holes in her shirt. This is an example of personification, when a speaker gives human attributes to something that is nonhuman. Breasts cannot "try" to do anything because they do not have their own will or intention. However, this description also helps to explain why the men find this woman so attractive.