This device appears to be an Automatic Transfer Switch (ATS), often used in electrical systems to manage power sources. It automatically switches between a primary power source (like the grid) and a secondary source (like a generator) in case of a power outage.
The buttons and digital display show settings and parameters such as voltage, status, and modes. The labels (L1, L2, L3, N, IN, OUT) correspond to the wiring terminals for input and output connections of the phases and neutral in the electrical circuit.