what a supervariable is basically boils down to its a variable that can hold seperate peices of information, such as a list, but it works with cloud variables, which is something a list cant do. so now, you can make your game hold 10 players instead of 5. also its capable of doing more than a game that can hold 5 players can do, such as having the players have their directions, usernames, etc being recorded. you just add what you want before the username, such as a number going from 0 to 9 to check what item you have or another number to check size.
the code here can be used in any project as it checks what the x and y position of a sprite and then puts that into a variable. there are no other things it can fiddle around with unless you make it change something such as a player.