Teaching English as a second or foreign language
Teaching English as a second (TESL) or foreign language (TEFL) and teaching English to speakers of other languages (TESOL) are terms that refer to teaching English to students whose first language is not English. The terms TEFL, TESL, and TESOL distinguish between a class's location and student population, and have become problematic due to their lack of clarity.
Source: Wikipedia — Teaching English as a second or foreign language (CC BY-SA 4.0)