What happens if I turn on sync on Android?

Can you explain what exactly happens when I enable sync on my Android device? I'm curious about the implications of this feature and how it affects my data, privacy, and overall user experience. Will my contacts, calendar events, and other sensitive information be automatically updated across all my devices? What kind of control do I have over what's being synced, and is there any risk involved with turning on this feature? It would be great if you could provide a clear and concise overview of the sync function on Android.