This module is based on the LM1117-3.3V regulator chip. It is a fully assembled board to provide a fixed 3.3V output and up to 1A of current with bulk capacitors at both input and output side of the regulator and a basic heatsink. If you are using this close to the 1A limit for an extended time, the heatsink may be replaced with a larger one plus active cooling with a fan may be needed. But for general purpose, low power applications, the default heatsink will suffice
There are terminal blocks for the input and outputs and it also comes with a DC input Jack for quick connection to a power supply adaptor.
There are also unpopulated header ports for the Vout and Gnd. See the back side of the board for the labels.
We also have a 5V version of this module.