On my Word doc there is a dark black line going across it. When I put my cursor on it, it shows a long equal sign with up and down arrows coming from the center. What does it mean? How can I get rid of this line?

The line indicates the top of your page. It does not print.
Elusive White Space by Suzanne Barnhill

I'm supposed to be updating someone else's Word doc. They will not give any help because I'm to learn by myself.
This time I've gotten a Format text effects column on the right side of the doc and I can't get rid of it. If I had any idea of what I am doing, I'd really be dangerous.

Basic rule: If it does not print, do not worry about it.

Basic Concepts of Microsoft Word - by Shauna Kelly
This link is about Word in Windows but the concepts are the same and many of the methods are the same.