what is six sigma in management? how could I get knowledge about it?

Answer 1

The six sigma method simply is one is fixing a target, two finding processes to attain your target, three meassuring your target through a feedback, four finding out if you are on track five if not on target changing your processes and six attainging your target.
This is nothing other than the good old management control system they used to design before six sigma was invented.

Answer 2

0.34 defects in 1 million product is called six sigma.

six sigma is a management technique which is used to achieve Zero defects.

depending upon the quality and defects grades are been awarded like black belt etc.