Aging of South Korea means that there are more and more people who are over 65 years old living in South Korea. This is because the birth rate (the number of babies being born each year) is low, and people are living longer, so more people are old. This means that there are fewer young people to work and look after the older people, and it can be hard for the government to pay for all the things that elderly people need, like medical care and pensions.