Okay, kiddo, have you ever seen a printer before? You know that thing that prints out your drawings and school projects? Well, sometimes when grown-ups use big printers in their offices they might see an error message that says "PC Load Letter".
Now, this might sound really confusing, but it's actually pretty simple! "PC" stands for personal computer, which is the kind of computer that most people have at home. "Load" means to put something into a machine, like when you put a toy in a toy box. And "letter" refers to a specific size of paper that you can use in a printer.
So when that error message comes up, it means that the printer is looking for a specific size of paper called "letter" that someone forgot to put into the printer. It's kind of like when you're looking for a specific puzzle piece but you can't find it because someone didn't put it back in the box where it belongs.
So, to fix the problem, you just need to find some "letter" sized paper and put it into the printer. Then the printer will be able to print out whatever the grown-ups need without any more error messages! Easy peasy, lemon squeezy!