It is a number derived by complex calculations after analysing your performance in all subjects. It takes into consideration your scores, your topic coverage in each subject, your accuracy, the types of questions you have attempted (easy/medium/hard), etc. So it is basically a weighted average number of your ‘status’ on where you stand with your preparation for the UPSC Prelims. If you are in green, you’re good. If you’re in yellow, you’re moving there. Orange and red mean you really need to buck up and work harder.