ELL can mean two things; it can stand for English Language Learning, which is the program, or it can stand for the students- English Language Learners. Students that are ELLs typically are students entering the American school system after just moving here from another country. However, students that were born in the United States, but speak another language at home can also be considered an English Language Learner.
ELL is taught in English and used as a support for students entering into a class taught entirely in English.