It protects a single-phase final subcircuit against overload, short-circuit, and earth leakage in one DIN-rail module.
The 10 mA IΔn is the key spec here — that's a high-sensitivity residual current rating, typically specified for circuits where additional protection against electric shock is required (e.g., socket outlets in bathrooms, construction sites, or wet locations). The C-curve (16 A) gives a magnetic trip threshold of 5–10× In, suited for loads with moderate inrush like small motors or fluorescent lighting banks.