accessibility

I'm using https://webaccessibility.com/ to check web accessibility, I get to 89% with one error. The error is Ensure the language of a document is set

<script>

Added the code to the header.php (<html lang="en" xml:lang="en" xmlns= "http://www.w3.org/1999/xhtml"&gt:wink: . But still get error, any ideas where i'm going wrong please. I will open access