That means this contactor is specified for panels that see dust, humidity, or non-condensing conductive atmospheres, not just clean climate-controlled rooms. The -25 °C lower limit applies for outdoor or unheated enclosure installations in cold climates.
Main circuit terminals accept 2x (0.5 to 1.5 mm²) solid/stranded or 2x (0.75 to 2.5 mm²), plus AWG equivalents 2x (16 to 12) and 2x (14 to 8). The minimum permissible conductor cross-section is 10 mm² at both 40 °C and 60 °C — that is the smallest wire that carries the rated current without exceeding the terminal temperature rise, not a wiring convenience limit.