An impound lot is where taken things wait to be reclaimed. Dream books read it as something of yours held by others, which you must make an effort to get back.
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.