It indicates the previous week high and low. When overlaid on the daily chart, it give buy and sell signals (in the understanding you have made a trade setup). Buy when the price crosses the previous week high, sell when it crosses the previous week low.
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 publication is governed by House rules. You can favorite it to use it on a chart.
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