The crosshair is convenient to become agile with your trading analysis and get information in a faster way. To enable the crosshair, click in the line studies toolbar. Then, move the mouse cursor towards a chart bar or candle, you should see the crosshair, which highlights a specific price and time.
Similarly, you can use the crosshair to measure time, bar and pips distances in a chart, this is useful for doing your analysis or determining potential Stop Loss and take profit levels. Left-click the chart while the crosshair is enabled and move your mouse while keeping it clicked: