The 66 kA Icu at 220…440 V AC (IEC 60947-2) is the maximum fault current it can interrupt once and remain functional; the Ics rating of 65 kA at the same voltage tells you it can clear that level repeatedly without needing service. Rated insulation voltage is 1000 V AC and operational voltage 690 V AC, so it handles standard 400/480 V systems with margin.
Fixed mounting on a base plate, rear connection, with a connection pitch of 115 mm without spreader. The 4-pole configuration has the neutral on the right. Dimensions are 537 mm wide by 352 mm high by 297 mm deep — account for that depth when laying out the enclosure depth and gland-plate clearance. IP40 protection means it is splash-proof from solid objects larger than 1 mm but not sealed against water ingress; install in a dry indoor switchboard or add a weatherproof enclosure for outdoor use.
Designed and tested to IEC 60947-2 for air circuit breakers. Suitability for isolation is confirmed per that standard, meaning you can use it as a visible-break disconnect. Electrical durability is 6000 cycles at 440 V without maintenance (Category B), and mechanical durability is 20000 cycles with maintenance. Maximum breaking time is 25 ms, closing response time 70 ms.