An accessibility statement has two basic functions.
Firstly, it presents clear information about how accessible the website is for people visiting the website who may have disabilities. It also enables the website owner to acknowledge any areas of the website where accessibility targets may not have been met and to outline the proposed plan for resolving any such problem.
Secondly, it is a powerful declaration of commitment. People visiting the website, particularly those with disabilities, will appreciate the open acknowledgement that accessibility is a key driver for the website.