AC-4 at 400 V is 8.5 A, covering reversing or plugging duty on smaller motors. If you're coordinating upstream protection, type 2 coordination calls for a 25 A gL/gG fuse; type 1 allows up to 63 A. Pollution degree 3 means it's happy in a typical industrial panel — some dust, some conductive grime — but keep the front IP20, so no washdown spray.
Screw-type terminals on the main circuit accept 2x (1...2.5 mm²) solid or stranded, up to 2x 10 mm² max. The auxiliary contacts (2 instantaneous, NO/NC arrangement) take 2x (0.5...1.5 mm²) or 2x (0.75...2.5 mm²). Strip length isn't stated in the spec, but standard 8–10 mm works for this terminal class. Side-by-side mounting is allowed — no gap needed between contactors — but allow 6 mm to adjacent components for heat dissipation.