Purgatory is the waiting place between, and dream books read it as a stage of cleansing or atonement. It often reflects a period where you feel you are paying off an old mistake before moving on.
Has this come up in your dreams before? What was going on in your life then?
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.