This is a high quality AC to DC ‘wall wart’ which produces a regulated output of 12VDC at up to 600mA. These are switch mode power supplies which means the output is regulated to 12V and the capable output current is much higher (600mA!).
These will power most projects that don’t require more than 650mA of current. Center-positive 5.5x2.1mm barrel connector.
Works with 100-240VAC inputs.