The Siemens SENTRON 5SY7263-6 is a 2-pole miniature circuit breaker rated 63 A at 35 °C with a B-curve trip characteristic — meaning it trips between 3 and 5 times rated current, suited for resistive and general-purpose loads where short inrush isn't expected. That's the number that governs coordination with the upstream protective device. The 63 A rating is at 35 °C ambient. At 40 °C it derates to 59.16 A, at 50 °C to 55.06 A, and at 60 °C to 50.65 A. That's the real continuous current the breaker will carry without nuisance tripping.
Mounting position any — vertical, horizontal, upside-down, doesn't matter for the trip mechanism. The 76 mm depth is standard for the SENTRON 5SY series — no surprise when you're laying out the DIN rail.