Trading cards are little pieces of cardboard with pictures of different things that people like. Sometimes they have pictures of sports players, but there are other kinds of trading cards, too. For example, there are trading cards with pictures of superheroes, TV shows, animals, and lots of other fun stuff.
When people collect trading cards, they try to get as many cards as they can to complete a set. This means they want one of each card in the collection. Sometimes, people trade cards with each other to try and get the cards they need for their collection.
Non-sports trading cards usually have pictures of things that aren't related to sports. For example, you might find a trading card with a picture of your favorite TV show character or a cool car. People collect these cards because they enjoy the pictures and want to have a full set.
Overall, non-sports trading cards are like collecting stickers or pictures of different things you enjoy. You try to find as many as you can and trade with friends to complete a set.