This indicator uses the concept of the "Opening Range" to create a Fibonacci zone from the high and low set during a specific time period after open (Defaults to 9:30 - 10:05 AM, EST)
The Opening Range is a popular tool for intraday technical analysis. Price frequently uses these levels as support/resistance, and a breakout from within the range can be a sign of further movement.
The Fibonacci levels are set such that the opening range high/low fall on the +/-0.5 fib. This creates an "extended range" outside of the opening range that may be useful during breakouts.