What do you speak? If you speak Portuguese you'll get by, if you speak Chinese (probably Mandarin but I'm not 100% sure) I think there's signage.

The guy above me said it all very well. But it all depends on how long the layover is.

The food court is small, crowded, and fairly expensive, unless your home currency is equivalent or valued higher than the USD.

The airport is decent, but there's just not much to do, unless you want to "duty free" shop. Again the problem is, it's pricey because of the USD. Not only that, but last 2 times I was there, they weren't taking credit cards. I asked why and I was told they had some problem with the company and that was it.

DON'T go down the stairs, that's customs.

Find a way to get into the COPA Club, it's not great, but there's comfortable chairs, desks to sit/work at, good wifi and booze. The bathrooms aren't great, they're small and crowded as well. I've never used the showers there but I've spent lots of hours in that lounge, I just load up some content on my laptop or use the wifi to stream.