WhatsApp has been testing the ability to make voice and video calls on the desktop for the last few months. But now it's getting a wider release. Like with the app, voice and video calls are end-to-end encrypted, making sure only those talking to each other will have access to the call's contents.
Group calls aren't available on the desktop yet, but WhatsApp plans to introduce the feature in the future. To use video and voice calls on the desktop, you will still need a mobile WhatsApp account.
Source: MacRumors