The Framework.Now() function returns current UTC time, in milliseconds, according to the computer clock.
It is therefore almost entirely equivalent to new Date().valueOf(). However, the framework includes a time check with the MyTrader server, and watches for computer clocks which are materially wrong (current threshold: >30 seconds wrong). One of the most common issues it picks up is a clock which the user has changed to local time without adjusting the computer's time zone. The result is that the computer clock shows the "correct" local time to the user, but its calculation of UTC is hours out.
If the framework detects a problem with the local clock, Framework.Now() will return an adjusted time, correcting for errors in the local clock.