ya for school , exactly, GCGB which I think Ian introduced to me when I started with PICs! Is a compiler for PIC, in it there are settings for the config bits, the rest of it are blocks, I imagine that other flow coders would be similar,. If he is saying flow code I imagine that would mean he may know how to set config bits and be familiar with structuring code, what this may not include is syntax and operators.
idk about app inventor, but i tried programming android using eclipse & java, definitely more tedious than windows desktop forms