Okay, imagine you have some little toys called quarks. They're really small and they live inside things called protons and neutrons. Now, each quark has a special type of property called strangeness which is a funny name but basically means they're a little bit weird.
When you have a lot of quarks all packed together really tightly, like in a super hot and heavy experiment, they all start bumping into each other and getting really excited. They get so excited that they can break free from their protons and neutrons and form what's called a quark-gluon plasma.
This plasma is like a big, squishy soup made up of lots of little quarks and their buddies, the gluons. It's really hot and energetic, kinda like the inside of the sun! Scientists study it to learn more about how the universe was right after it was created.
So to sum it up, quarks are little toys that live inside bigger toys called protons and neutrons. When you get a bunch of quarks really excited, they make a weird type of soup called quark-gluon plasma. Scientists study it to learn about the early days of the universe.