You might not have noticed because your browser does not properly
support soft hyphens. Or none of the words on the page needed any
hyphenation when you looked at it. Or the effect was just to subtle and
nutural to catch your attention. Or you didn't hear or feel anything
special. But the page which has this button on it is trying to use soft
hyphens to let browsers break words at certain points and improve the layout
that way.
If you're also using soft hyphens on your site to improve the layout you
might want to use the following code in your page to show the button to let
people know you're trying to improve their experience.
More info on this fascinating subject