Any app or device can help make money in one way or another. The WhatsApp application on the cell phone can help people make money if they use it in a right way. For instance, they can promote their business or service on the WhatsApp through forwards. Others will be able to see it. After that, they will call or contact you about your services. They may then tell others about your business. You can add links and videos.
So, you can sell items on WhatsApp by uploading the links to your website or uploading videos or photos about your products on WhatsApp. Sometimes, you can help other companies by advertising for them. Then you place it on your WhatsApp. You will always need to increase your contacts in order to get more potential buyers.