Okay, let's imagine you're watching a cartoon on TV. The cartoon is called Spiderman, and during the commercial break, you see an ad for Spiderman toys. Now, the people who make Spiderman toys would like to sell more of them, so they pay some grown-ups to do something called "media context studies."
A media context study is when the grown-ups look at things like the TV show or the magazine where the ad is going to appear, to try and figure out if it's a good place for the ad to be. They want to make sure that lots of kids who like Spiderman will see the ad, and that they'll be in the right mood to want to buy the toys.
They might think about things like: What time of day is the show on? What other shows are on around it? What kind of people usually watch this show? Are they boys or girls, or both? How old are they? Do they like action figures? Do they have money to buy Spiderman toys?
All of these questions help the grown-ups figure out if the show is a good "context" for the ad, meaning a good environment where the ad will make sense and be more likely to get kids excited about the toys. It's kind of like picking the right ice cream flavor to go with your cake, you want both to be tasty together!