Okay kiddo, you know how sometimes you or your friends get really mad and start shouting and being grumpy? Well, imagine if there was a whole group of people who got mad and wanted to change things because they thought the grown-ups weren't doing a good job.
In South Korea, there were a lot of young people who felt like their government wasn't listening to their concerns and wasn't treating everyone fairly. They were really angry and frustrated about it, so they started protesting and making loud noises to get attention.
These young people became known as the "angry young men." Even though some of them were women, they were all called that because it was a term that had been used before for a similar movement in another place.
They used social media to organize themselves and make sure other people knew what they were upset about. They would hold up signs and chant slogans, asking for things like better jobs, better education, and more equality.
Of course, not everyone agreed with what they were saying, and there were some people who didn't like all the noise they were making. But the angry young men didn't let that stop them. They kept speaking out and making their voices heard.
Eventually, some of the things they were asking for started to happen. The government listened to their concerns and made some changes to try to make things better. It wasn't perfect, but it was a step in the right direction.
So that's basically what the angry young men in South Korea were all about. They were a group of young people who were really mad and wanted things to be better. They made sure everyone knew how they felt, and they managed to make some changes happen.