The floor is the ground you stand on, read as stability, basic security and what supports you day to day. Lying on the floor stands for feeling low or simply needing to rest.
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.