In Hattrick Global is a blanket term used to refer to the entire game, as opposed to only a single country. For instance, Canada's Season 15 is the Global Season 27, since this is the 27th season for the entire game, but only the 15th Canadian season.
"Global" is also used to refer to the Global (English) conference, where the most commonly heard phrases include English only in Global, xxxx is evil and the ever popular idea threads. The Global conference is known for having an extremely high volume of posts and new threads, of which an extremely low percent are intelligible or relevant.
Artist's conception of the Global conference: