What does it mean to have your nexus rooted?

I have done as you suggested multiple times prior to my post. All of the contacts in my phone are marked as Google contacts but when I attempt to merge them with Google the phone says there are no Google accounts to merge. All when I attempt to edit the contacts, changing the type of contact is not an option.

At some point I recall changing the color of the g in a gmail icon from purple to yellow. But now all of the events I enter in the calendar are in the same yellow and are difficult to see. I have looked and looked but can't find where I did this. Any ideas?