Essentially, Scout showed tolerance by dealing with her aunt Alexandra when she comes to visit the family. Scout displayed tolerance by avoiding retaliation against her Aunt. Although her Aunt was telling her that she was being raised wrong and that she was too much of a Tomboy, Scout also showed tolerance by listening to her father.
Harper Lee illustrates understanding in To Kill a Mockingbird through Jem's realisation regarding Mrs. Dubose, the children's change in perspective about Atticus, and through the children's discovery of the truth about Arthur “Boo” Radley.
I hope this helps!