While it's true modern-day South Koreans don't use Chinese characters (hanja [1]) at all in their day-to-day life, there are still a few places where they show up, as it was the most common writing system in Korean up to the late 19th century. Most notably, most Korean names can be written in hanja and almost all Koreans know how to write their own name that way at least. South Korean kids also study hanja at high school to some extent.

[1] https://en.wikipedia.org/wiki/Hanja