Lang attribute is used to declare language for screen readers and search engines. The lang means language which can be any language Lang attribute is always is used in <html> tag.
<html lang=en
>Content</html>
Here en is two letter language name which means english language.
Open notepad or any other text editor, follow the following points.
save file with name task.html or task.htm and then open it using any browser and see results.
In above task en means english language and US means the United States