My 7 year old sister’s friend is teaching her about sex?

How do I protect her? She said her friend told her in her ear at school what it is and when I asked what it is she said idk it’s kissing but I don’t know if she’s just saying that to hide it from me. Whenever she sees a pretty girl she said that girl is gross she probably kisses and does saxe (sex) with her boyfriend. She also said girlfriends and boyfriends are disgusting because you have to kiss and do saxe with them.

She has an iPad and gets curios and I’m scared she’ll look it up and find out what it is. She’s too young. It’s a good sign that she told me she stopped being friends with that friend because dirty and is only going to be friends with the clean one.

I want her to be at least 10 till she learns. I don’t want her to throw her childhood away and lose her innocence.

Any idea on how to protect her? Already put on restrictions and parental controls on her iPad.