The Siemens 5SU1356-1DA06 is a combined residual-current and miniature circuit breaker (RCBO) — an FI/LS protector — in a 1+N-pole format. The pig-tail neutral connection is a factory-fitted flexible lead, not a busbar stab — factor that into your panel wiring plan.
The 70 mm depth (D=70MM) is the dimension from the DIN-rail mounting surface to the front of the device — standard for Siemens 5SU series RCBOs. The 1+N-pole width occupies a single modular unit (roughly 18 mm per pole, but confirm the exact width from the product drawing for your busbar layout). The pig-tail neutral exits the bottom; plan your neutral busbar routing accordingly to keep the bend radius within the enclosure's wiring space.