Stardates Explained - 20171208.2012

You don't understand the startdates?

Take, for example, 20171208.2012

Let me stick some spaces in some helpful places:

2017 12 08 . 20 12

That better?

20171208 means 8th December 2017, and 2012 is in 24-hour clock format, IE 8:12PM

Stardates in the Star Trek universe work in an entirely different way. Wikipedia has a good explanation on how Stardates work.