The different colours of the dashboard symbols typically mean the different levels if attention needed by the driver. The green (or sometimes blue) symbols inform you how or what system is running. The amber symbols mean that there are some parts of the vehicle which need attending to and should probably get repaired soon. The red tells you that there is a serious safety issue that needs correcting immediately. A few examples of these are:
The most popular symbol on the dashboard. It informs you (and other drivers on the road) that you have your indicators on and want to change direction or lanes.