In Korea, there is a special name for each year called an era name. It's like a special nickname for a year that helps people remember it. The era name changes whenever a new king or queen takes the throne.
So, let's pretend you're a king or queen in Korea. When you become the ruler, you get to choose a name for your era. It's usually a short and easy-to-remember phrase that represents your reign, like "Great Harmony" or "Prosperous Peace."
Once you choose an era name, everyone in the country starts using it to refer to the current year. Instead of saying "2021," they would say "Year of Great Harmony" (if that was your chosen era name).
This tradition has been around for a long, long time in Korea. It helps people remember important historical events and also gives each year a special meaning.