What Does the Parable of the Lamp and the Bushel Mean?

Clean Cut: Episode Directory
nameunderheaven...
Clean Cut; Episode 554
What does it mean to be the light of the world? What's a bushel? What would happen to a candle put down under a bushel?
All well-reasoned comments welcome.
If you're new to the series, I hope you'll check out the previous episodes, as they contain a lot of deductions, which I'll be building on.