"Beginner readers" refers to people who are just starting to learn how to read. They are at the beginning stage of reading and are just starting to explore and understand written words and sentences. Full definition
The words only go in three directions that are beginner reader friendly. (apples4theteacher.com)
A teacher's main concern is to help young beginner readers to develop not only the ability to recognise words, but the skills necessary to understand what these words mean. (newscientist.com)