Why use Output Module/ Dual Relay Module?
Dual Relay Module
This module contains two relays that are electrically isolated from the controlling input. The relays can be used to switch higher voltage and current loads than a microcontroller can traditionally accomplish.
Model No : VF- 6052-00
UL File NO : S6659
Brand : VES (Viking Electronics System)
Certificate : UL Listed & FM Approved
Made in USA/ UK, Shipment from USA
Explanation: The Relay (Dual Channel) is used for controlling a circuit by one signal or when many circuits must be controlled by one signal. Thus making it a primarily switching device.
The relay module is an electrically operated switch that can be turned on or off deciding to let current flow through or not. They are designed to be controlled with low voltages like 3.3V like the ESP32, ESP8266, etc, or 5V like your Arduino.