The LX1D4G5 is a TeSys-series contactor coil from Schneider, designed to replace the coil on a matching contactor in the LX1D4 family. It operates on a 127 V AC 50 Hz control circuit.
What the rating means
The 127 V AC 50 Hz control voltage is the coil's pick-up rating — it must see that nominal voltage to pull the contactor in reliably. If your panel runs 120 V AC or 127 V at 60 Hz, the coil may not hold or may overheat; this part is strictly for 127 V AC 50 Hz circuits.