Hi Sharon, English as a second language is called ESL                 (English Second Language). There are lots classes for students who come from another country to United Sates for education. Their first language is their mother language (Spanish, Persian, Chinese,...). They cannot talk English very well, so they use to take ESL classes in order to improve their English. There is program called Rosetta Stone for students who cannot speak English or they want to improve their English. This program has many languages that students can take,  and learn. This program is also for students who want to learn another language.
Most of ESL students take the program and more than half of them successfully passed the ESL system and take the regular English. This program also has the Korean language as well. I hope this may help you and answers your question. Thank you!,

Hi Sharon,

There are a lot of ways for your friend to learn English.  It really depends on his language learning needs:  

1.) Language Software: Great for travelers or for nurturing an interest in a language and/or culture.  However, true proficiency isn't likely.  Language requires interactions between people.  Though the programs can be helpful at laying down a foundation, becoming nuanced in the subtleties of a language is extremely difficult if you take away the human factor.    

2.)  General and Intensive English Program (GEP & IEP): Great for students/professionals who want to study English for business or academic purposes.  These English programs are usually a total immersion classroom--English is the only language spoken.  In most of these programs there are speakers from all over the world, making English the only common language.  If you live in larger city or urban area, they are pretty easy to find.  However, they are less prevalent in more rural areas.  The only difference between General and Intensive Programs is the the type of Visa needed.  GEP's require a Tourist Visa and IEP's require a Student Visa (F-1).  If he is on a Tourist Visa, he is only allowed, by law, to study about 15-18 hours/week.  If he's on a Student Visa, he is required to study about 22 hours/week.  If he's on a J-1 Visa, a Work Visa, I'm pretty sure he can do either, but don't quote me on that :)  If your friend has American citizenship, then he is free to choose whichever works best for him.  The only drawback is that these programs can be awfully expensive.  Again, depending on where you live, you might want to shop around and find the best program for the best price.  

3.)  English Language Learner Volunteer Programs:  There are also many community outreach programs that offer free language services.  You can check out the community center or church in your area to see if they have any programs for him.  It's a great, free option.  And, it might be a good way to supplement a software program so that he's getting the conversational English practice that he needs.  

Just for good measure, below are some terms that might help you search for the right method.  Often times, these things go by many names:

Abbreviations:
ESL: English as a Second Language
ELL: English Language Learners
EFL: English as a Foreign Language
TESOL: Teachers of English to Speakers of Other languages
TEFOL: Test of English as a Foreign Language (Academic Test)
TOEIC: Test of English for International Communication (Business Test)

Schools:
Kaplan International Program (KIC) or Kaplan English Program (KEP)
St. Guilles
Intrax
EF Education First
GEOS
Berlitz

I hope that was helpful :)