Sure, this wikipedia article is pretty accurate[1]. It comes down to a series of pretty complex issues between South Korea and Japan. Although the current boycott is usually talked about in the news as a result of what SK perceives to be an unfair trade relationship, the tension amongst the average person I talk to comes down to the lack of apology by Japan over comfort women, and more recently the Liancourt Islands[2]. Japan has updated it's High School history curriculum to state the Islands are owned by Japan and not mentioning the disputed status, while SK teaches about the dispute. As a result of all of this, many many Koreans won't shop at Japanese brands[3]. (I am not Korean however I live in Korea)
[1] https://en.wikipedia.org/wiki/2019%E2%80%932020_Japan%E2%80%...
[2] https://en.wikipedia.org/wiki/Liancourt_Rocks_dispute
[3]https://en.wikipedia.org/wiki/2019_boycott_of_Japanese_produ...