The above graph shows the Bundfuture with 2 hours candles. The horizontal dots represent its possible support (magenta) and its possible resistance (dark green). Below this is the volume (red = more sell orders; light blue = more buy orders) per candlestick and on the bottom window you can also see an average of its range (high to low).
As you can easily see, the market changes from a calm to a lively event and then back again. This can also be seen in the respective volume and the trading range.
The whole thing in itself can represent a trading system. I leave the interpretation to the reader, because every person will see something different and draw conclusions from it.