To receive and respond to a text message using Python, Flask, and Twilio, you need to set up your local environment with Flask and Twilio installed. You create an app.py file that imports the necessary libraries, sets up a route for handling POST requests on the '/sms' URL, and uses the Twilio library to generate a response TwiML that tells Twilio what to do next. The app needs a publicly accessible URL, so you use ngrok to open a tunnel to your local machine and generates a custom forwarding URL that you point to in your Twilio console. When someone texts your Twilio number, Twilio makes an HTTP request to your app, which responds with the response TwiML, and Twilio sends a reply message back to the original sender.