A sphere is complete in every direction, a small world of its own. A glowing or floating one is traditionally read as inner wholeness, or as an idea so self-contained it needs nothing added.
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.