That rating tells you the contacts are built for the hardest switching duty, not just running current. For AC-2 duty (starting and stopping slip-ring motors), it handles 37 kW at 400 V. At 500 V it carries 45 kW, and at 690 V it carries 21.1 kW — so the same contactor covers a range of line voltages common in European and export panels.
The main current circuit uses screw-type terminals; stranded wire up to 50 mm² or solid up to 2.5 mm² per clamp. Front protection is IP20 with a cover or box terminal; the terminal area itself is IP00 — meaning the wiring compartment is open and needs enclosure protection.