I couldn't really understand what more we learned from her other than the fact she seemed to be upset about the death of Tom.
I think that we learn that Alexandra has more going on than say women like Miss.Grace Merriweather. There is a genuine concern for her brother and his children. Her ignorance seems tempered by a sense of right and wrong that isn't completely different from her brother. She tries to do the right thing within the context of her understanding. Much of her concern appears veiled behind Southern prejudice and ignorance but as she spends more time at the Finch residence, we see a more human side of her (like her concern over Tom Robinson).
