looping operation multiple data folders

I am trying to loop over data folders and do operations within each folders, ( so something like 2 for loops maybe? )

In attached image , folder "tests" contains number of folders "NearbyR_xy" each folder contains 2 waves. I want to do operation on each wave within folder ( e.g. "NearbyR0xy" )  and want to repeat it for the rest of the folders. What is the easiest way doing this?

The way I was thinking doing it , first defining a "for loop" for  each folder "NearbyR..." then another "for loop" to do operation within each wave (for example making waves and adding them to existing waves or some simple operation that would involve second looping)

Thank you,