The value returned is the time in OLE DATE format. Summarizing from the Microsoft documentation describing that format:
0.0 of OLE DATE is midnight, 30 December 1899. The integer part of the number is the number of days since 30 December 1899. The fractional part is the fraction of the day, starting from midnight -- i.e. 0.5 is noon, 30 December 1899.
If you're using MFC or ATL (C++), the COleDateTime class does the dirty work for you. If you're using VB.Net, the DateTime.FromOADate method will get you what you want.