Volume Bars are the familiar red and green bars. A green bar indicates that the closing price is higher than the close of the previous bar while a red bar indicates that the closing price is lower than the previous close.
Volume bars adjust automatically to the selected time frame (e.g. daily, hourly, weekly). A 50-bar simple moving average displays on the volume bars so it easy easy to identify if a bar is above/below average volume.
Unusually high volume days produce spikes in the volume indicator that make it hard to see the relative volume activity on other days. To compensate for this, you can set the display to truncate the bars on any day where the volume exceeds the average displayed volume by X times. Place a check in the box to truncate volume bars that exceed the average by X times. In this example we’ve set it to truncate any volume bars that exceed the average displayed volume by 3 times. Choose a color so the tips of the any bars truncated will show that color.
Read more on the importance of Volume at Investopedia