ESL is defined as English As A Second Language. People who are not native speakers of English are learning it as a "second" (or third or fourth or ...) language.
Koreans have special challenges when learning English - there is no "v" or "z" or "r" sound in the Korean language. And the sound of Korean is less complex, so that there are not many consonant sounds together when compared to English.
Here are some videos on learning English. We will add more videos & lessons later, along with translations into Korean of some key ideas from each video.