The WhatsApp Business API from Twilio allows developers to communicate with users on the popular messaging app. To send a picture on WhatsApp using JavaScript, you need Node.js installed on your machine, a free Twilio account, and a smartphone with an active WhatsApp account. You can connect your smartphone to the Twilio sandbox by sending a message with a specific code and then set up a new JavaScript project, installing the required dependencies and creating environment variables for your Twilio credentials. The code provided creates a Twilio client using the stored credentials and sends a WhatsApp message with a body and an image URL, printing the message SID to the terminal after it's sent.