This is a Tina MVC front end controller page.
When the Tina MVC plugin is active this content will be overwritten.
If Tina MVC is active, and you can read this from the public side of a Worpdress page (i.e. not from the ‘Page edit’ admin menu) then
Tina MVC may have ‘lost’ this front end controller page (this can happen if you edit this page from within WordPress), deactivate and reactivate Tina MVC to fix this.
If Tina MVC has been deactivated then this becomes a ‘normal’ WordPress page and therefore you can read this text.
You can safely delete or hide it.