A superior good is something that people want more of when they have more money.
For example, imagine you get a raise and now you have more money. You might choose to buy fancier things like organic food, a nicer car or better clothes. These things cost more, but since you have more money, you can afford them.
On the other hand, if you had less money, you might have to choose cheaper options like non-organic food, a used car, or clothes from a discount store.
So, a superior good is something that people want more of when they have more money, and less of when they have less money.