Volume chart, what is meant by green and red coloured chart

I am a little confused with the volume chart. Here is a screenshot:

  1. What is meant by green and red colour?
  2. Does the green colour means that the volume increased by x number over the last minute volume and volume decreased by x amount over last minute volume? Or the colours simply mean the buy and sell volume?

Thanks. I am new to trading.

Nothing to do with Traded Quantity, the logic works as on the thread above.