Lean Six Sigma is a methodology that teaches how to eliminate waste of all kinds, within an organization. The education certifies you as an expert on efficiencies in the workplace. When it comes to Six Sigma certifications, there are a variety of levels which you can obtain. You begin with white, and work your way up to yellow, green, and black, with the highest option being MBB (Masters' Black Belt). Share with the interviewer if you are Six Sigma certified. If you are, discuss how far you have taken your certification. If you do not have your certification, show enthusiasm for the idea and express that you are open to expanding your professional knowledge and training.