In to kill a mockingbird, "Summer was on the way; Jem and I awaited it with impatience. Summer was our best season: It was sleeping on the back screened porch in cots, or trying to sleep in the treehouse; summer was everything good to eat; It was a thousand colors in a parched landscape; but most of all, summer was Dill."(Lee 38)

explain the function of the colon

The colon in this sentence serves to introduce a list of reasons why summer was such a special season for the characters. It sets up the reader to expect a series of examples that illustrate the importance of summer to Jem and Scout. By using the colon, the author is able to clearly signal to the reader that a list is about to follow.