The 800 A frame gives you headroom: the breaker's physical bus and contacts are rated for 800 A, so the 600 A trip unit can be swapped up if the load grows, without replacing the whole breaker. It's a 3-pole unit with fixed front terminals (FF) and carries UL and CSA marks, so it's accepted in North American panel builds without extra paperwork.
The XT6N frame is a standard panel-mount MCCB — it bolts to a mounting plate or backpan, not a DIN rail. The fixed front terminals (FF) mean the line and load connections are at the front face, which simplifies bus-bar routing in switchboards and panelboards. In a typical industrial distribution panel, this breaker would feed a motor control center or a downstream subpanel. The 3-pole configuration covers three-phase loads.