Alright kiddo, so in Stargate SG-1, a meridian is a special place in the human body called the brain.
Now, when people travel through the Stargate, they’re going to different planets which can have different kinds of air or even different kinds of gravity. And that can make people sick or hurt their bodies.
So the people in SG-1 have found a way to use a special machine called the Ascension machine to make someone’s body better and stronger. And when someone’s body is really strong, they can go to the meridian.
The meridian is a special kind of training camp for people who’ve gone through the Ascension machine. They exercise their brains there to become even stronger and smarter. But only the bravest and strongest people can handle the meridian, because it’s pretty hard work!