The script is written to help the "Resistance and Support Trade" utility (https://www.mql5.com/en/market/product/6620)

If dropped on any bar of the chart, a line with the name "Res" will be automatically created at the High of that bar. If the script is dropped on an empty place of the chart or simply the "Attach to a chart" is run, the line will be placed at the High of the last formed bar.

The "Resistance and Support Trade" utility (it active) will trade the upward breakout of the resulting line.