My interpretation of this is a junior SDE position where you mostly update system configuration parameters all day instead of writing code or designing systems. People in these positions still get paid SDE salaries but aren't gaining any useful software development experience.
A galley was a large-ish, primarily oar-powered ship.
However it also refers to the kitchen on certain even larger boats.
So, it's kind of ambiguous what GP meant - either picking a cook out of a galley-kitchen (who is not the best chef, but rather someone making huge amounts of food for a ship's crew), or picking a slave off of the oars in a galley-ship.
What does this mean?