Twilio provides a serverless environment that enables developers to quickly develop and deploy Twilio-specific functions using TypeScript. To send an SMS or WhatsApp message with Twilio Functions and TypeScript, developers need to set up a Twilio account, obtain a phone number, install the twilio-cli and typescript globally, and create a Twilio Function in TypeScript. The function uses the Twilio client to send a message to the specified number. After setting up the base project, developers can test their functions locally and deploy them to production using the npm run deploy command.