The Siemens 5SJ6504-7 is a SENTRON 5SJ6 miniature circuit breaker — 1P+N configuration, rated 4 A at 240 V AC with a C tripping characteristic.
The 4 A rating governs the continuous load — use it on circuits where the full-load current stays below 4 A, with headroom for ambient derating up to 45 °C (the listed ambient range). The 1P+N pole arrangement switches the line and switches the neutral, but does not protect the neutral; that's standard for single-phase final circuits where the neutral is a switched, not protected, conductor. The 6 kA breaking capacity is the same under both EN 60898 (household) and IEC 60947-2 (industrial) standards, so the same part serves both distribution board and panelboard applications without requalification.