Apparently Speaking Calendar is a typical calendar you place on your Windows desktop, and where you note down all your pending tasks and appointments you want to remember.
The big difference with Speaking Calendar is when the moment comes to advise you of these appointments or events with a sound, as it replays a piece of text you wrote, but audibly. This way it gets your attention much more effectively.
In the Speaking Calendar you can activate as many alarms as you want. Thus you can program these alarms by the hour day, week, month or even year.