My friend is currently working as a relationship manager with Indusind bank looking forward to become branch manager in an year or so, so in a way he shall be shifting from sales to operations, will Six Sigma be beneficial for him at this stage considering his goal? Please guide me.

Six Sigma is extremely useful in operations.

The big reason for Six Sigma's success in operations is that output from operations can reliably be made more and more predictable with usage of Six Sigma.

Also when you are a branch manager, you shall have opportunities of improving Branch's performance in many ways. You should be able to consider Black Belt soon after Green Belt to gain bigger benefits in your new role.

Six Sigma qualification and skill-set is the most useful single program that prepares a candidate for a cross functional shift. As the techniques are same across industry sectors, it also helps in cross - industry shift. I have seen hundreds of professionals shifting industry and function (aided by SIx Sigma competence) which would otherwise be considered impossible.