What “truth” about Dill is learned in this chapter? Does that affect your feelings towards him as a character? Does it make you understand his lies better?

In this chapter, we learn that Dill doesn't have a home.... a real family life. As a result, we can understand why he would choose to lie and make a family up for himself.

“Grandma says he hasn’t got a home—”
“Has too, he lives in Meridian.”
“—he just gets passed around from relative to relative, and Miss Rachel keeps him every summer.”
“Francis, that’s not so!”
Francis grinned at me. “You’re mighty dumb sometimes, Jean Louise. Guess you don’t know any better, though.”