Range can be 15 mins ,30 mins ,1Hr as selected by the user.
HIGH are marked as red because it act as resistance.
LOW are marked as green because it will act as support.
In true TradingView spirit, the author of this script has published it open-source, so traders can understand and verify it. Cheers to the author! You may use it for free, but reuse of this code in a publication is governed by House Rules. You can favorite it to use it on a chart.