What the line is
The ABB 1SAZ201501R0003 is a solid state overload relay carrying a 110 V supply designation per the listing title, filed in the Solid State Overload Relays subclass under Relays and the Circuit Breakers, Fuses & Protection parent category — the role on a BOM is motor protection sitting between contactor and load.
Where the class is used
Solid state overload relays in this ABB family typically pair with a matching contactor to give a motor starter its overload element; the 110 V designation on 1SAZ201501R0003 is the control supply the relay expects, not the line voltage it monitors, so the wiring diagram for the panel must keep control and power circuits on separate conductors.