For EFL/ESL students to understand what they read, they will need to sort unfamiliar sounds into fragments that make sense. Like decrypting a code, learning the sounds of letters or letter combinations can help students decode the words as they spell and read.
By decoding words, the student starts to develop word recognition, which, in turn, improves reading fluency.
By improving reading fluency, the student will also improve reading comprehension. This will help students concentrate on making meaning from the text they read, as they will no longer struggle with decoding words.