She didn’t  know what an obliviate was, but it soon became pretty clear. He used the spell and as her Aunt’s eyes turned glassy, he told her that she won’t remember what happened and  believe Edalinn was at a friend's house. Edalinn thought that was a funny excuse because of two reasons. Number one, the Dursleys would never allow her to go to a friend’s house and number two, she had no friends. 