An eraser is read as the wish to undo something said or done. Dream tradition also sees it as forgiveness — clearing the page so that something better can be written.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.