The 30 kA breaking capacity at 400 V AC per IEC 60947-2 tells you this breaker can safely interrupt a fault current up to 30,000 amps without welding its contacts or blowing apart, which is important for industrial panels fed by a transformer with stiff secondary capacity. It also carries a 5 kA interrupting rating per UL 1077 and CSA C22.2 No. 235, so it's accepted in North American control-panel applications as a supplementary protector. The 2-pole unit (2P) switches both lines on a single-phase circuit or one leg of a three-phase system; it doesn't switch the neutral. Rated voltage is 400 V AC between phases, and it handles up to 72 V DC maximum, so it can also serve in DC control circuits within that limit.
The terminals accept combined (box lug / pin) conductors top and bottom, and the unit is sealable for applications requiring tamper-evident locking.