Will deselecting the sync button on my itunes erase EVERYTHING on my phone?

I have the "sync music" box under music checked for my iPhone/iTunes settings.

It always syncs my music to my phone and takes forever to finally get connected to my itunes.

When I go to deselect the box, it says:

"Are you sure you do not want to sync music? All existing songs and playlists on the iPhone will be removed."

Although it says it will delete only music, I've never done this before and I fear it will erase everything on my iPhone. I'm okay with it erasing my music and playlists, but everything else needs to stay.

Has anyone done this? And does it only erase music?

Thanks.