The Siemens SIRIUS 3RT5935-5AF01 is a magnet coil — the replaceable solenoid that pulls in the contactor armature. It's rated 110 V AC at 50 Hz, with a tolerance band of 0.8... 1.1 times the rated voltage, so the coil holds in reliably as long as the control supply stays between roughly 88 V and 121 V. The control supply voltage type is AC, so don't feed it DC unless you want a smoking coil.
This coil snaps into the SIRIUS contactor range — it's the field-replaceable part, not the whole contactor. If you're swapping a failed coil on an existing SIRIUS contactor, verify the contactor frame size and coil voltage match. The 110 V AC 50 Hz rating is specific; a 110 V 60 Hz coil won't hold in correctly on a 50 Hz line, and vice versa.