S.H.
Get her (and you) the "American Girl" book series.
It is JUST for girls, this age. Tweens.
There are many GOOD topics and about hygiene.
To be read by the girl and her Mom.
It is not intimidating and age appropriate. Nothing graphic.
But informative. Factual.
Any bookstore has it.
My daughter is 9. She has lots of these books, which I got for her.
She LOVES them. And she likes talking WITH me about it. We read it together even.
She is even reading one right now in fact!
She tells me, to tell you, (she is here as I type), to go get it!