This lecture explores the different modes of Thymio, a robot that uses proximity sensors to perceive and react to its environment. The instructor demonstrates how Thymio behaves in yellow, green, red, and dark blue modes, showcasing its ability to avoid obstacles, communicate with other robots, and sense its position in space. By using a microphone, Thymio can also react to external sounds, transitioning between states based on the number of claps. The lecture illustrates how Thymio functions as a finite state machine, capable of performing various actions based on different inputs.