when atticus comes into jem's room before bedtime to speak with the children, what information does he relay to them from aunt alexandria?

I think the original text says it best;

"Er-h'rm," he said. He was beginning to preface some things he said with a throaty noise, and I thought he must at last be getting old, but he looked the same. "I don't exactly know how to say this," he began.

"Well, just say it," said Jem. "Have we done something?"

Our father was actually fidgeting. "No, I just want to explain to you that - your Aunt' Alexandra asked me . . . son, you know you're a Finch, don't you?"

"That's what I've been told." Jem looked out of the corners of his eyes. His voice rose uncontrollably, "Atticus, what's the matter?"

Atticus crossed his knees and folded his arms. "I'm trying to tell you the facts of life."

Jem's disgust deepened. "I know all that stuff," he said.

Atticus suddenly grew serious. In his lawyer's voice, without a shade of inflection, he said: "Your aunt has asked me to try and impress upon you and Jean Louise that you are not from run-of-the-mill people, that you are the product of several generations' gentle breeding --' Atticus paused, watching me locate an elusive redbug on my leg.

"Gentle breeding," he continued, when I had found and scratched it, "and that you should try to live up to your name--' Atticus persevered in spite of us: "She asked me to tell you you must try to behave like the little lady and gentleman that you are. She wants to talk to you about the family and what it's meant to Maycomb County through the years, so you'll have some idea of who you are, so you might be moved to behave accordingly," he concluded at a gallop.