English as a Foreign Language, or EFL, refers to learning and using English as an additional language in a non-English speaking country. It can be compared with ESL and ESOL, which refer mainly to learning English as a new resident in an English-speaking country.

Example
EFL includes short summer courses in an English-speaking country, such as the UK, Canada or the US.

In the classroom
EFL materials tend to be written for learners either studying English in their own country or on a short course in an English-speaking country. ESL materials tend to focus on ‘survival English' for people now living in an English-speaking country.

Further links:

https://www.teachingenglish.org.uk/article/exploring-uk-esolefl-divide

https://www.teachingenglish.org.uk/article/a-personality-orientated-approach-efl-teaching

https://www.teachingenglish.org.uk/article/elt-efl-elf-eap