This is an LM7805 Voltage Regulator module that can be used to provide stable power supply to an Arduino. It has a heatsink to get rid of any excess heat that may build up during usage. The module provides a constant 5v output voltage with a maximum output current of 1.2A no matter what the input voltage fluctuations (such as that found when using an external Lead-Acid or Lithium Battery or even solar panel).
