TEFL stands for Teach English as a Foreign Language. This distinguishes it from the English subject which is taught to native speakers at school or university. It’s basically teaching people who’s first language is not English how to read, write, speak and understand the English language.
You might also come across the term TESOL, but there’s really no difference. It stands for Teach English as a Second or Other Language.
For many, TEFL is a way to see another country, to travel and to meet new people. It might be something they do for a short period of time. However, it’s also highly addictive, and there’s a worldwide TEFL community composed of teachers who’ve dedicated their lives to this profession.