Trip curve C means the magnetic trip operates between 5 and 10 times rated current (200–400 A for this 40 A unit), which suits motor-starting loads, small transformers, and general-purpose distribution where inrush isn't extreme. It's not the soft-start-friendly curve D, but for most mixed-load panels this is the standard pick.
At 3 poles it takes up three modular units of width (roughly 54 mm on a standard 18 mm/module rail), so plan your enclosure fill factor accordingly. The S800S platform uses a common trip bar across all poles, so a fault on any one phase opens all three — no single-phasing risk on motor circuits.