The Siemens 3RT1935-5AH22 is a SIRIUS magnet coil — the replaceable solenoid that pulls in the main contacts on a Size S2 contactor. It's rated for 48 V AC control supply at both 50 Hz and 60 Hz, with a holding-current draw of 0.8... 1.1 A across that frequency range.
The 48 V AC control voltage is the nominal coil rating — the contactor will pull in reliably at that voltage and hold in across the 0.8... 1.1 A range. The 50/60 Hz dual-frequency rating means the same coil works on either supply without derating. If your control transformer is 48 V AC at 60 Hz, this coil is a direct fit; if you're running 50 Hz, the holding current stays within the same band.