The Siemens 5SU1356-1KV13 is an FI/LS protector — a combined residual-current device (RCD) and miniature circuit breaker (MCB) in one unit, Type AC, sensitivity 30 mA, breaking capacity 6 kA, 1+N poles, C-curve, 13 A rated current. It sits on a DIN rail in a distribution board, sized at 70 mm module width. The Type AC designation means it detects sinusoidal AC residual currents only; for pulsed DC or mixed-frequency fault currents you'd step up to Type A or F.
The 6 kA breaking capacity covers typical domestic fault levels; if your installation's prospective short-circuit current exceeds that, you'd need an upstream backup fuse or a higher-rated version.