So you know how there are these special gases called noble gases like helium, neon, argon, krypton, xenon, and radon? Well, these gases are called noble because they don't like to react with other stuff.
Now, sometimes these noble gases can react with other things and form something called a noble gas compound. It's like when you and your friend mix two different colors of Play-Doh to make a new color - except in this case, the noble gas is reacting with something else to make a new compound.
But it's not easy for the noble gases to do this! It's kind of like trying to mix oil and water together - they just don't want to mix. So when a noble gas does react with another element, it's usually under special conditions like being in a high-pressure environment or being really cold.
So, to sum it up: noble gas compounds are when a special gas that doesn't like to react with other stuff finally does react with something to form a new compound. It's kind of like mixing two different colors of Play-Doh, but a lot harder and more special.