Welcome to the forums, kavv23.
The author of a page can name their CSS classes anything they choose, and for some reason they chose the name "hiddenH1Text" for this class. What this class actually means is defined elsewhere - either in an external .css file or in the <head> area.
It would be rather foolish to try to game search engines with hidden text and then advertise the fact so boldly right in the code. Then again, people do foolish things.