When describing the altercation between Roger and Mrs. Jones—after Roger has tried to steal Mrs. Jones’s purse—Hughes uses a hyperbole, as seen in the following passage:
Instead of taking off full blast as he had hoped, the boy fell on his back on the sidewalk and his legs flew up. The large woman simply turned around and kicked him right square in his blue-jeaned sitter. Then she reached down, picked the boy up by his shirtfront, and shook him until his teeth rattled.
The hyperbole here—in which the narrator describes Mrs. Jones’s shaking Roger “until his teeth rattled”—uses exaggerated language in order to help readers understand the ferocity with which Mrs. Jones fought back against Roger's attempted mugging. It is not possible for teeth to rattle (since they are firmly in place), but the expression communicates that Mrs. Jones is incredibly strong and uses such strength to overpower Roger and teach him a lesson.
This hyperbole, along with the description of Mrs. Jones kicking Roger “right square in his blue-jeaned sitter,” is significant because it shows how, despite the compassion Mrs. Jones shows to Roger later in the story, she is not willing to let him get away with his harmful actions. To Mrs. Jones (and likely to Hughes as well), kindness involves a combination of both self-protection and empathy towards others.
In the opening lines of the story, Hughes uses a hyperbole, as seen in the following passage:
She was a large woman with a large purse that had everything in it but a hammer and nails. It had a long strap, and she carried it slung across her shoulder. It was about eleven o’clock at night, dark, and she was walking alone, when a boy ran up behind her and tried to snatch her purse.
The hyperbole here—in which the narrator describes Mrs. Jones’s purse as containing “everything in it but a hammer and nails”—helps readers understand why Roger targeted her for mugging. It is not possible for Mrs. Jones’s purse to contain everything in it except for a hammer and nails, but the exaggerated language encourages readers to picture a large and full-to-the-brim purse that a petty thief like Roger would understandably want to target. The fact that Mrs. Jones was walking alone at 11 at night likely also made her an easy target.
Roger soon realizes after attempting to take Mrs. Jones’s purse that the heaviness is actually a liability—as Hughes notes later in the scene, “the boy’s weight and the weight of the purse combined caused him to lose his balance.” Roger losing his balance is what enables Mrs. Jones to overpower him, leading her to drag him home, feed him, and ultimately show him compassion that even he feels he does not deserve.