Removes extra Font Awesome stylesheets added to your theme by several plugins, if Font Awesome is already loaded by your theme.
Dequeue Font Awesome is a very lightweight plugin that will remove all Font Awesome stylesheets added to your theme by certain plugins, to not be loaded by several times, if your theme already make use of Font Awesome.
For instance, if you use a theme that use Font Awesome and you also have 2 active plugins (e.g. social icons, menu icons) that both load Font Awesome too, you will end up with 3 font-awesome.css stylesheets loaded. But you only need one. This plugin helps you to always load only one Font Awesome.
Dequeue Font Awesome plugin aims to reduce the number of HTTP requests (for performance reasons) generated by certain plugins that loads extra Font Awesome stylesheet to your theme, even if your theme already uses Font Awesome.
You wouldn't want to see Font Awesome loaded several times in your header, bloating your theme unnecessarily.
Dequeue Font Awesome plugin can be also used safely as a smart way to enqueue Font Awesome stylesheet from CDN, even if your theme doesn't use it yet.
So there is no need to find out if your theme already uses Font Awesome, the plugin will load it only once anyway, thus preventing any additional HTTP requests generated by other plugins that uses Font Awesome too.