The 6 kA breaking capacity (rated per both EN 60898 and IEC 60947-2) tells you it can safely interrupt a fault current up to 6 kA at 400 V AC without welding its contacts or cascading upstream. The 60 V DC maximum rating (per pole) means it can also serve in DC control circuits up to that voltage.
Mounting and integration — DIN-rail fit and panel constraints
Installation depth is 70 mm. Occupies 2 width units. Ambient temperature range is -20 to +45 °C for normal operation, with periodic excursions to +55 °C and up to 95% humidity. If your panel sits near a heat source or in direct sun, derate the 25 A rating above 45 °C — the B-curve thermal trip element will shift. Storage range is wider (-40 to +75 °C), which governs shipping and idle spares, not running conditions.