Again, You need to explain the story more and please, Think before you type.
So, Both two little girls were playing, the girl looks at the sky and sees a cloud and says she sees her grandmother and her aunt? Thus making you believe in... invisible friends or ghosts?
Also, I told my children about about my family because they are all in Australia and they only see them on skype once in a while. I even told my daughter about my grandfather's life, his likes, his past and how he went to Australia from scottland with his family and start a new life for them.
My daughter had told my sister in law kids about my grandfather and in turn my sister in law asked me about him and guess what? I told him he had past away before she was born. She didn't think they saw a ghost.
So logically, She most likely heard about her grandmother and five year olds say the darnest things.