It's rated 20 A in AC-1 utilisation category at 440 V, meaning it's sized for resistive loads — heaters, lighting banks, or transformer primaries — not motor starting. The 24 V DC coil with built-in bidirectional peak limiting diode suppressor means the control circuit is protected from flyback, and the coil holds between 0.7 and 1.3 Uc, dropping out between 0.1 and 0.7 Uc below 50 °C. This part is now obsolete per the manufacturer, so it's a last-time-buy or surplus-channel item.
The 20 A conventional free air thermal current (Ith) at 50 °C is the thermal limit for the power circuit — don't exceed it in continuous duty. The rated operational current (Ie) is 20 A at 690 V AC in AC-1, but note it derates to 16 A at <70 °C ambient.