A space is the term used to denote a defined area within an Interact Server, and this can be anything from a specific course, to a general news and information area. You can also have sub-spaces, so some spaces may be used for nothing more than organising spaces into a hierarchy.
As a space admin you are able to add and modify/content to an existing space for which you are an administrator, but you can't add new spaces to the system, this can only be done by a server admin.