Subscriptions are regular renewed orders so the same products are bought by the customers automatically and they don't have to do it themselves. Also, it can be used to give customers access to a restricted part of the web site during their subscription is active.
The list view provides a paged list of all available subscriptions, which can be filtered by various, subscription-related criteria. The most important columns are shown by default but the list of columns can be adapted via the list header. Subscrptions can be edited by clicking on the list item.
Contrary to other list views, you can't add a subscription directly because they are based on ordered products and it would be too difficult to create them from scratch. Instead, you can create a new subscription by clicking on the calendar icon in the left "Renew" column of the ordered products list.