The coil holds at 24 VDC nominal; dropout is below 18 V, so you get a clean break on undervoltage without chatter.
The 10 A rating at 24 V is for DC-12 / resistive loads at that voltage — handy for control circuits or small DC bus switching. For motor duty, the AC-3 rating at 400 V is the one that matters: 4 kW, which covers a standard 5.5 HP motor at 460 V (derated slightly). The 4.5 kW at 500 V and 5.5 kW at 690 V tell you this contactor is comfortable on 480 V and 600 V class systems as well.
The 45 mm width is the S00 footprint — fits alongside other SIRIUS components on the same rail. Side-by-side mounting is allowed, but keep the 6 mm side clearance for airflow if you're packing them tight. The spring-loaded terminals accept 2x (0.25 to 2.5 mm²) solid or stranded, or 2x (24 to 14 AWG). Strip length is 8 mm; no ferrule needed for solid, but ferruled stranded is cleaner for maintenance pulls.