The propeller stands for the driving force that turns effort into forward motion. Spinning freely, it is read as momentum; stalled or tangled, as energy that cannot find its way into progress.
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.