From Annabelle: Do you have any advice on how to explain death to a young child and how to get them to understand it? She's four years old and her grandmother has died. She has a brother who is two years old, but we didn't even really try with him.
At four years old, she'll know that a loved one has gone away, but she won't understand the concept of death being final. To her, it'll almost be as if grandma's gone on a long holiday. So, you may periodically get questions from her asking, "is she coming back soon?" And you can tell her, "Grandma's gone to heaven and she's going to stay there." Or whatever your particular belief system is. You'll be able to support your belief system with spirituality, drawing her attention to the sky and the stars.
It's also good that you (sporadically) spend time looking through photos with her and tell her memories, so she will remember her grandma and, when she gets older, she will feel like a part of those stories and remember the telling of them. Don't avoid conversation about grandma; let her talk about her grandmother and the love that's there.