Imagine you're trying to bake a cake, but you want to make sure you have all the ingredients and steps figured out before you actually start baking. That's kind of what desk checking is like. It's a way to double-check your work before you actually put it into action.
For example, let's say you're doing some math homework. Before you turn it in, you might go through and re-do each problem to make sure you didn't make any mistakes. That's a form of desk checking.
The same goes for computer programming. Before you actually run your code (which means letting the computer read it and execute it), you might go through and read your code carefully to make sure everything looks right. That way you can catch any mistakes before the computer does.
Desk checking can help you catch mistakes and avoid problems later on. It's a good habit to get into, whether you're baking a cake or writing computer code!