That means it can exchange events and other information to show you the content of your Google Calendar or iPhone/iPad calendar and allow you to modify it. To sync with Google Calendar, CalenGoo needs to run its synchronization.
Today I will talk about syncing Google Calendar with your iPhone 3G (Since I have the iPhone 3G). It is pretty simple and all it requires is a user name and login to a specific site. This site does all the syncing, the only problem I found was it kinda drains battery fairly quickly.
If you have a Google Apps for Business or Education account you can continue to use Google Sync tool but there is an even easier way to sync your Google calendars and iCal on your iPad and iPhone (or both).