Color codes.
The lamp is either EU or Asian. Brown is live, blue is neutral and green/yellow is ground.
In the U.S., green is neutral (easy), black is live and white is neutral.
We are only dealing with "L1", "N", and "ground" or "earthing" here.
It's not a massively huge deal if you wire them opposite (because it's AC), but you shouldn't, and bad things can still happen.