I was confused at first until I played around some.
I'll try to explain.
Under Play Lists (in iTunes) it makes a folder called, "My Devices" and then under that it makes a Play List called ... whatever. In my case it made a Play List called, "Android" (see image below)
Now in order to sync music or podcasts etc. you MUST copy them into that Play List (in my case the one called "Android") for it is only stuff in THAT singular Play List that will sync.
A word to the wise. If you want albums to stay together, especially albums with 'Various Artsits' then I suggest the following "trick" which worked for me.
Click on the album cover in iTunes (do this before you add it to the Play List). Sorry when I say click on it I mean do a 'right click' which brings up a menu. On that menu select the option called, "Get Info"
Oh I guess now is a good time to say I'm using Windows (not Mac) and I use Grid view (Albums) which shows a thumbnail of each album.
So OK we click on "Get Info" and this brings up a dialog window. The window looks like this:
The default is that everything on this screen is set to "No" and there are no checkmarks. So basically you want to change it as I have here. By doing this you ensure that the album stays "together" and is in a single folder (once it gets to your Android). Even if you put multiple albums on this one Play List, each will be in it's own folder and therefore "together" once it gets to the Android.
But there is one last thing you need to do to make sure this all works (and and after you make the change above make sure you click that OK in the lower right hand corner).
The last thing you need to have set "just right" is the setting in
iTunes Agent called, "Synchronize Pattern"
Make sure that is set to "iTunes" and not one of the other two choices.
Do all this and everything will copy to your Android in a fashion that makes sense. Otherwise it kinda splits stuff up into Artist folders and it can get real ugly. Makes it impossible to play an album back that way.
Hope this helps.