Okay kiddo, so a moniker is like a nickname for someone or something. It's like when your parents call you a silly name like "Scooter" or "Pumpkin". It's not your real name but it's just something fun that they call you.
Monikers can also be used for places or things. Like a city might have a nickname such as "The Big Apple" for New York City. Or a car might have a nickname like "Betsy" or "The Beast" to make it seem more fun and friendly.
So basically, a moniker is just a cute and fun way of referring to someone or something else without using their real name. It's just like how you might call your teddy bear "Fluffy" even though that's not its real name.