Watercolour is read as softness and flow — colours that bleed and blend beyond full control. Dream books link it to gentle emotions and to accepting what cannot be painted over once it is on the page.
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.