This is a very powerful feature in Word which is almost unknown to the world. Here are the articles which explain the practical benefits of using sections in Word.
Unknown but extremely useful: SECTIONs in Word
How to insert landscape page in a regular Word document
Word Sections – Part 2 – Partial Multiple Columns
Word Sections – Part 3 – Headers and Footers
How to create a formal document in Word?
Enjoy!