Understanding Load Profile in AWR reports

Hello everyone, 

I was trying to understand the part of the Load Profile section in the AWR reports.

There are some resources out there when we search in google, however, when I searched for the "W/A MB Processed" I couldn't find anything.

What I assume right now is that W/A means Work Area.

But how do I explain this "W/A MB Processed"?

What does the value per second and per transaction tells me about?

Where else in the AWR reports that I can crosscheck?

Please shed some light on me. I really appreciate your answer.

Thank you.