The small red line and green line after the last set of candles are indicating the Low and High based on the Time Frame.
If you are looking at a short time frame interval chart, you will see Daily Low/ High. Likewise, the Daily Chart will give you weekly Low/High, the weekly chart will give you monthly Low/High.
Sometimes chart candles may scale due to Low/High price. You can uncheck Low and High option to turn off once you know their price.
Most investors buy back at New Low and sell at New High.