In Korea, there are two major holidays:
1. Korean Thanksgiving, known as Chuseok in Korean
2. Lunar New Year, known as Seollal in Korean
Seollal (설날) looks like seolnal, but is pronounced seollal in Korean. When an ㄴ sound follows a ㄹ sound, its pronunciation changes to ㄹ to make it easier to say.
Seollal falls on the first day of the Lunar New Year calendar. It is usually towards the end of January or beginning of February on the Western (solar) calendar.
In 2016, Seollal falls on February 8th; in 2017, it falls on January 28th; and in 2018, it falls on February 16th. Although Seollal itself is only one day long, the days either side of Seollal will also be public holidays. The exact number of days for the Seollal holiday depend on which day of the week it falls on.