Borax is an old household cleaner, read in dreams as the urge to scrub away what has built up. It can stand for practical solutions and getting a situation back in order.
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.