COLUMNS are finally available in Google Docs!
Select Format -> Columns option allows you to add the columns to your document.
You can select 2 or 3 columns for your document
Once you have your columns inserted, you can go to more options to set your margins and spacing between columns, you can also add a line in between your columns:
If you select the line it will appear as you start the second column of text and will look something like this: