The GY801 module is a 9-axis motion tracking device that includes a 3-axis accelerometer, a 3-axis gyroscope, and a 3-axis magnetometer (compass). It can measure acceleration, angular velocity, and the Earth’s magnetic field in 3 dimensions. The module is often used in applications such as orientation sensing, movement detection, and compass navigation. The GY801 module likely contains the necessary sensors and additional circuitry for interfacing with a microcontroller or other device.