Kshemendra is one person's name, just like yours or mine. He is a real person who works in the United States government, helping to make sure that different groups can share information safely and securely.
Imagine you have some toys you really like to play with, but you also have a little sibling who is not supposed to play with those toys. Your parents might tell you to keep those toys in your room, where your sibling can't get to them. That's kind of like what Kshemendra does for important information that different groups want to share with each other, but don't want just anyone to be able to see.
Kshemendra helps create rules and guidelines for how different groups can exchange information, while keeping that information protected from people who aren't supposed to see it. Think of it like a secret handshake or password that only certain people know, and that allows them to share important information with each other without worrying about anyone else finding out.