A hashtag sorts things under a label, so it is read as being categorised or wanting to be seen by many. Dream books link it to the pull of trends and public opinion.
When this appeared in your dream, what were you feeling?
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.