The Siemens SENTRON 5SL6504-6CC is a 1P+N miniature circuit breaker with a B-curve tripping characteristic, rated at 4 A and 230 V AC, with a 6 kA breaking capacity per EN 60898. It switches the neutral conductor, so it's a single-module-width (2 MW) unit for residential or infrastructure panels where you want overcurrent and short-circuit protection on the phase with a switched neutral. Rated frequency is 50 Hz.
B-curve means the magnetic trip operates at 3 to 5 times rated current — 12 to 20 A for this 4 A unit. That's the standard for residential lighting and general-purpose socket circuits where you don't have high inrush from motor loads.
Screw terminals with a specified tightening torque of 2.5 to 3 N·m.