What does language function in ESL reading mean?

Language function refers to the role or purpose for which certain language is being used within a larger piece of text. Understanding language functions are a core component of the reading process as they directly tie into why an author has written something. In terms of ESL reading, it refers to the ability of English language learners (ELLs) to identify and comprehend the intended purpose of specific words, phrases and sentences within a reading selection.

Some common language functions used in English texts to which ESL students should pay attention for when reading include main ideas, elaboration of details, supporting ideas, opinions versus facts, cause and effect analysis, comparing and contrasting concepts, sequential events (e.g cause/effect, problem/solution) among others.