A circle drawn for protection is read as a boundary — a safe space for change or reflection. Dream books see it as the wish to keep certain influences out while you do inner work.
Where in your waking life have you met something like this lately?
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.