It protects a single-phase line against earth faults and overloads/short-circuits in one 36 mm-wide module, saving a DIN rail position compared to separate RCCB + MCB.
Temperature derating — the real current rating on your panel
The 16 A rating holds only at 30 °C ambient inside the distribution board. At 40 °C it's 15.2 A; at 50 °C it drops to 14.4 A; at 60 °C it's 13.6 A; at 70 °C it's 12.32 A. The full curve is on the nameplate; don't spec it at 16 A unless you can guarantee the 30 °C ambient.
Two modular width units (36 mm) snap onto a DIN rail. Depth is 77 mm, height 90 mm, installation depth 70 mm — fits standard distribution boards and sub-distribution panels. Degree of pollution 2 and overvoltage category III are standard for fixed-installation distribution boards.