In the 8th episode of "Relax with Excel," the podcast introduces the CONCAT function in Excel, a tool for joining two or more text strings into one. The episode explains how to use CONCAT through a step-by-step guide, starting with entering sample text in cells, selecting a cell for the CONCAT formula, and entering the formula with its arguments. It demonstrates joining texts and adding spaces for readability. This episode is designed for both learning and relaxation, catering to listeners whether they are awake or asleep.