The Space used screen gives you an overview of the amount of content you have uploaded to your SportzVault site.
The basic SportzVault service allows for a certain upload limit (this is usually 25 or 50 MB), and once this is exceeded, no further uploads are allowed until files/images have been removed to bring the space used under the limit.
Alternatively, extra space can be purchased - please contact support for further details.
The total space used is a total of the space used from your site:
Any news/events items you create are not counted in the allowance - you can effectively create as many of these as you like, however the size of each item does have restrictions (that are unlikely to be exceeded unless the item text is extremely long!)