Garbage is read as what has been used up or no longer serves — old habits, thoughts or relationships. Dream books take a pile of it as a sign that something asks to be cleared out.
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.