Accessibility statement is a way to display your (user-oriented) accessibility efforts, commitment to accessibility in general and what measures are you (or your business) taking to offer your content in an accessible way.
It should really not be a copy-paste from some well-formed site that you or your consultants happened to find but I suggest you really dedicate some time and effort to write down what are you doing to achieve accessibility for your web presence and beyond.
W3C organization has prepared a very good article on the subject of accessibility statement (opens in new window) and they even went beyond with making a simple generator tool to help you with the key design and form concepts for your own accessibility statement (opens in new window), but I am begging you to really make your business and map all your accessibility weaknesses and commitments for accessibility in the future.
Accessibility statement as a regulatory requirement
European Union (EU) is even requiring all public bodies in countries inside EU to provide the accessibility statement as a part of it’s Web Accessibility Directive (WAD – opens in new window) in paragraph 44 and other regulatory requirements on it can also be found in other countries.
(44) | An accessibility statement should be provided by public sector bodies on the compliance of their websites and mobile applications with the accessibility requirements laid down by this Directive. That accessibility statement should include, where appropriate, the accessible alternatives provided for. |
Please check my accessibility statement here. It is still a work on progress as I am still researching best practices for it.