In act one of the play, when Rebecca Nurse steps into the room, Hale indicates that he knows her, not personally, but by reputation. Rebecca has a reputation for being very wise, prudent, loving, righteous and upright; when Hale sees her, he says,
"It's strange how I knew you, but I suppose you look as such a good soul should. We have all heard of your great charities in Beverly."
This lets us, as the readers know, that Rebecca Nurse is a good person, so good in fact, that she even looks good in physical appearance. Her very physique radiates the goodness that she carries in her soul. Also, this helps the reader to know that Rebecca spends a lot of time in giving charity and service to other people; so much, in fact, that other towns have even benefitted from it, and heard of her kindness and generosity.
Miller does a great job of letting us know the nature of Rebecca Nurse in a very indirect way; the play has limited space, so we don't have time to follow Rebecca around to directly learn for ourselves that she is a good person. So, Miller inserts this little bit of conversation in so that we can gain, in an indirect way, a feel for Rebecca's character, without using taking too much time.
I hope that helped; good luck!