The ABB B6-40-00-01 is a 4-pole contactor rated AC1-12A with a 24 VA coil. It switches resistive loads up to 12 A per pole in the AC1 duty class — think heater banks or lighting circuits where inrush stays low. The 4-pole layout gives you an extra switching path for two-phase or three-phase-plus-neutral distribution without stacking auxiliary blocks.
The B6-40-00-01 is a DIN-rail-mount contactor. Four poles in a single package save rail space compared to ganging two 2-pole contactors. The 24 VA coil is standard for 24 VAC control transformers; verify your control supply can deliver the inrush without dropout on the rest of the circuit.