To give an easy visualization for most people (average Americans, really, because most other people in the world already know what a meter looks like), imagine that the average doorknob is about 1m above the floor, so imagine basically the bottom part of a typical interior door is about 1m sq. Now, make a square out of 18 of those pieces wide by 18 pieces high.
Americans will measure with anything but the metric system.
Except for those few of us who grew up interested in science, because science pretty much world-wide (even in the USA) uses metric for pretty near everything. I've used metric for my entire life, and been ridiculed for it that entire time by all the same morons that think any interest in science makes you a "nerd" even if you also happen to play and enjoy sports (despite almost the entire rest of the world standardizing on metric long ago), and despite the fact that most folks in the USA are already using metric themselves every single day. Yet somehow metric is "too hard to learn, waaah!" (It's based on tens, just like our money. Too complicated? Gimme a break!) Hell, our sugary fizzy drinks even all come in 1 and 2 liter bottles, FFS!
And if they do, they will call it things like "square doorknob".
I feel "about a 8 floor building" would be a good ROM :)
At that level of specificity, you could just say that a meter is "about a yard".
So very roughly a 300kW spotlight pointed at a relatively small area (wild guess at around 1km^2, anyone done the maths?)
Edit: A 5km diameter spot illuminated from 600km altitude.
Whoops, I overcooked my last minute edits while almost asleep. Yeah, I'm was off by 18x there.