Learning how to use and implement this indicator with your current strategy is the most important. First, you will note there are two lines on the indicator, one typically green and one typically red. When the red one is near 100 and the green one is near 0, that means the market may be shifting to a negative or bearish trend. Reversing the information works the same for a potential shift to a bear market. When the lines cross in the middle, that is your queue to be on the lookout for the potential setup of a market shift.
Some ways to use this could be with standard deviation or Bollinger Bands, allowing you to note where the market may or may not want to go. These types of indicators tend to work better on longer time frames, but you can edit the inputs and it may adjust well for quick trading intraday. One other way to use Aroon on your charts is if the market seems to be consolidating, you will note that both lines are below the 50 level mark. Again, these are not concrete indicators, but rather a time for you to look and evaluate a chart or current positions you may have in the market.