The triangle is read as the strength of three: body, mind and spirit, or past, present and future. Pointing up it suggests aspiration; in everyday speech it also recalls a tension between three people.
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.