The line looks like this
.. vim: set ft=help norl ts=8 tw=78 et :
And appears at the bottom of some text files, such as vim documentation.<
It is called a modeline.
See :help modeline for more information.
:help modeline
Basically, it is a way to tell Vim how to render a text file.
That is the modeline.
It’s called a modeline. Try: