Time_Offset: Different brokers are set to different server times, the EA needs to know what time it actually is in order to open and close trades at the right time of day. If this number is not accurate, the EA will open trades at the wrong time of day and probably lose money. If Download_Settings is set to true the EA will automatically determine the proper Time_Offset and display it on the chart screen. For most brokers the Time_Offset will be 0.
The Time_Offset will not be automatically determined by the EA if Download_Settings is set to false or if you are back testing. We will go over manually setting the Time_Offset in the back testing tutorial.