Masturbation is very normal at this age. Children discover it, and discover that it feels good. It’s hard to blame a kid for doing something that feels good.

However, it’s perfectly fine to put limits on it. You don’t want to make her feel bad or shameful for doing something normal, but it’s okay to discourage her from doing it in public. Explain that what she’s doing is fine, but that it’s a private thing she should do in her room.

If your daughter has delayed language skills or other developmental or behavioral problems, talk to her doctor. In these cases, the masturbation can be part of a bigger issue. If not, don’t worry about it. With some gentle guidance from you, this phase will pass.