The 15 kW AC-2 at 400 V rating tells you this contactor is sized for moderate motor loads in applications where the switching frequency is moderate — up to 750 operations per hour at AC-2. The AC-4 rating of 29 A at 400 V covers the worst-case inching duty, but at a lower maximum operating rate of 250 cycles per hour. If your motor is a standard squirrel-cage induction motor starting across the line (AC-3 duty), the contactor handles up to 1 000 operations per hour, but the AC-3 kW rating at 400 V is not listed in this evidence — you'd need to confirm that from the full datasheet. The front is IP20, so finger-safe when installed in an enclosure; the terminals are IP00, so they require a panel or enclosure to prevent accidental contact.
For solid conductors, each terminal accepts 2x (0.25 to 2.5 mm²). For stranded conductors, the range is 2x (0.75 to 25 mm²) for the main circuit, and 2x (0.75 to 16 mm²) for the auxiliary circuit. That covers most panel wiring from control signal leads up to motor feeder cables. The contactor dimensions are 55 mm wide, 142 mm high, and 130 mm deep — a compact S2 footprint that fits standard 55 mm-wide DIN-rail slots.