Facebook pixel allows you to receive information about the actions taken on your store to make your Facebook ads more relevant to your audience. Facebook pixel can help you understand the behaviour of people who visit your store and which advertising strategy works best to reach your business goals.
Tracked conversions appear in the Facebook Ads Manager and in the Facebook Analytics dashboard, where they can be used to measure the effectiveness of your ads, to define custom audiences for ad targeting, for dynamic ads campaigns, and to analyze the effectiveness of your website's conversion funnels.
Please find more information about how to install plugins here.
The plugin is provided absolutely for free and includes source code.