I've recently been wasting time on Empire of Code instead of doing productive and paying work.
Anyhow, the description of the Speed Boost puzzle Landing Holes was the most confusing thing I've ever read.
I'm pretty sure they're describing a Gatling gun. But then mentally
s/canon/breach/ and then the description starts to make sense.
As for the function, the first list is a list of barrels, the second is a list of working breaches. The puzzle is asking you for a list of how many times you can rotate the barrels so they align with working breaches.