Fenix, the secret area you discover via "Perception"
is that narrow hallway leading to the room with the shelves and the locker that is shown in your screenshot. This isn't a conventional Perception check, per se, because it does not actually check against your Perception
stat, but instead "checks" your ability as a gamer to be
perceptive. By wearing night-vision goggles, you are "increasing your perception," allowing you to better perceive the door in the wall leading to the secret room.
That's what Mac Orion meant when he said,
lol you run around with nightvision, take it away and you get it why you need perception for it 
In other words: try finding that room without night-vision goggles on and without already knowing it's there, and you'll understand, by how difficult such a task is, why it's like a perception check.
Does that make sense now?
