Three poles, rated 20 A continuous at 40 °C through 55 °C, and derated to 19 A at 60 °C through 70 °C. That flat thermal curve from 40 °C to 55 °C is unusual and useful: you get full 20 A rating across the typical panel ambient range without having to oversize the frame. The headline number here is the breaking capacity: 187 kA at 240 V, 121 kA at 415 V, 75.6 kA at 440 V, and 7.5 kA at 500 V and 690 V. At 415 V the 121 kA still covers most heavy industrial installations. The drop to 7.5 kA at 500 V and 690 V is the limit for higher-voltage motor circuits; if your system runs at 690 V, verify the available fault current stays under that threshold. The overcurrent release is a TM120M — thermal-magnetic, fixed-trip type. The '120M' designation means the magnetic short-circuit pickup is fixed at 120 A (6× the 20 A rating). That fixed magnetic setting is typical for starter protection: it allows motor inrush without nuisance tripping but still clears a bolted fault fast.
Dimensions: 130 mm height, 76.2 mm width (3 inches), 70 mm depth. Power loss is 12 W maximum at rated current. That is moderate for a 20 A MCCB; factor it into the enclosure thermal budget if you are packing multiple breakers in a small panel.