The Fuji Electric FRN0037F2S-4C is a FRENIC Series High Performance Inverter rated for 3.7 A on a three-phase 400 V supply. The enclosure is S = Basic type (IP20/IP00), meaning it's intended for installation inside a panel where the IP20 rating covers the body and IP00 applies to the heatsink area — standard for this class of drive.
The 3.7 A rating (code 0037) is the drive's nominal output current, typically matching a 1.5 kW to 2.2 kW motor at 400 V depending on the motor's efficiency and duty cycle. The three-phase 400 V input (code 4) is standard for European and Asian industrial mains.