The text explains a mathematical trick called the "Doomsday algorithm" which can be used to calculate the day of the week for any date. The author, Matthew Gilliard, presents this as a useful skill that can be practiced with an SMS chatbot built using Twilio Studio and a serverless function created with Twilio Functions. The chatbot is designed to send a random date in 2020 and ask the user to reply with the day of the week, allowing them to practice their skills. The author provides step-by-step instructions on how to create the chatbot, including setting up a Twilio account, creating a function, and designing a Studio flow. The chatbot is designed to be tested with an SMS number provided by the author, allowing users to practice their skills and potentially applying them in real-life situations.