Answer: It reveals background information about the Finch family, and also contrasts Scout's narration as an adult with her narration as a child.
Step-by-step explanation:
At the beginning of "To Kill a Mockingbird" (1960), Harper Lee's coming-of-age novel, Scout Finch, the narrator of the story, gives us an insight into the Finch family history. She describes that her antecedents came from England and settled in the United States. Scout's account of her family's history makes the family more familiar to the readers. It also implies that the family, having been in Maycomb for generations, is quite respected in the community.
It is also important to mention that the story is narrated from a perspective of a six-year-old girl, whereas the story about the family history is told by a grown-up Scout. Scout's description of the Finch family, therefore, provides a contrast between the way Scout perceives the world as a child and as an adult.