Assonance is repetition of similar vowel sounds in nearby words.
There is an example of assonance in the first line of the novel: "When he was nearly thirteen..." The vowel sounds in "he", in "nearly", and "teen" are similar.
Hyperbole is an exaggeration for effect. For example, in To Kill a Mockingbird, on page five, Harper Lee writes: "People moved slowly then. There was no hurry, for there was nowhere to go, nothing to buy and no money to buy it with, nothing to see outside the boundaries of Maycomb County." This is obviously an exaggeration, as people had to buy things to live--food, supplies, etc.--and there was an entire country outside of Maycomb County to see.
When Scout sees snow for the first time, she says, "Atticus, the world is coming to an end, please do something!" She is exaggerating for effect: the world isn't really ending, but she's as scared as she might be if it were.
Assonance is a method of achieving emphasis and cohesion in two or more words by repeating the same vowel sound in words that start with different consonants. One example of assonance in the novel To Kill a Mockingbird takes place in Chapter 9 when Scout says,
"But at supper that evening when I asked him to pass the damn ham, please, Uncle Jack pointed at me. 'See me afterwards, young lady,' he said" (Lee 50).
The vowel sounds in the words "damn" and "ham" are the same. Assonance is also located in the words "See" and "me" in the second sentence.
Hyperbole is an exaggeration that is used for emphasis in writing. In Chapter 11, Jem destroys Mrs. Dubose's camellia bush, and the children wait for their father to return home from work. Scout employs hyperbole when she says,
"Two geological years later, we heard the soles of Atticus's shoes scrape the front steps" (Lee 65).
Scout uses hyperbole to emphasize the fact that waiting for Atticus felt like a very long period of time.