The 'Re-Install Links' option makes it easier to ensure that when you activate a WordPress plugin on your site, that you're using the exact plugin files as they are found on WordPress.org
A fresh copy of the plugin means that it cannot have been compromised or edited in any way.
When the Plugin Guard sees you activate a plugin, it will analyse it and take a snapshot for future scans. The best practice for this is to ensure that the files are clean and original at the time of activation.
When this option is enabled, it will make 2 changes to your WordPress admin plugins page.
NOTE: These re-install options are only available for plugins that are installed from WordPress.org.
1. It adds a new link your plugins allowing you to easily re-install a plugin.
2. It adds a message to the "Activate" link letting you re-install the plugin right before activation.
To learn more about the Plugins and Themes Guard scanner in-detail and watch the explanatory video, please go here.