"Language proficiency" refers to the level of skill or ability someone has in using a particular language. It indicates how well someone can speak, write, understand, and communicate in that language. Full definition
This is usually based on a combination of performance on an English language proficiency test, grades, standardized test scores and teacher recommendations. (lansingschools.net)
The test is designed to provide information about language ability to speakers across a range of language proficiency levels. (thoughtco.com)
All students, regardless of language proficiency level, have the ability to think deeply about mathematical concepts. (blog.mindresearch.org)