Tag Feed Plugin Installation files and locations

The Instruction says…

2. Download the Tag Feed plugin file.

3. Unzip the file into a folder on your hard drive.

4. Upload tag-feed.php to /wp-content/

Most plugins are uploaded to /wp-content/plugins/.

This plugin MUST be uploaded to /wp-content/ using FTP.

My Question:

In the plugin there is a file global-tag-feed.php

and a subfolder named includes.

What are they for?