What it is on the BOM line
The ABB 1SAZ711201R1031 is a solid state overload relay in the manufacturer's 3-pole solid-state overload line, sold under Circuit Breakers, Fuses & Protection / Relays / Solid State Overload Relays. For a buyer who arrived with this exact order code, the procurement-relevant identity is the part number string itself (1SAZ711201R1031) — that's how it ships on the PO line and how it's traced back on the packing slip, not the generic class name.
Fit against the class
Solid-state overload relays in this class are typically wired downstream of a contactor to provide adjustable, electronic motor-overload protection — the three-pole form factor matches the standard line-voltage motor connection used in panel builders' motor-starter assemblies.