Okay kiddo, so methane pyrolysis is a big word, but basically it means that we can turn methane gas into other useful gases by heating it up a lot.
So, imagine you have a balloon with methane gas inside it (don't try this at home!). If we heat up the balloon really hot, the methane gas inside will start to break apart into smaller molecules.
These smaller molecules are called hydrogen and carbon. Hydrogen is a gas that we can use for things like fuel cells in cars or to make ammonia for fertilizer. Carbon is the same stuff that pencils are made of, and we can also use it to make things like car tires, plastics, and even medicine.
So, by using methane pyrolysis, we can actually make new materials and substances that we use in our everyday lives from a gas that is pretty abundant in nature. Cool, huh?