What is Software Serial | How to write the code | Arduino Tamil Tutorial

Code:-

#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11); // RX, TX

void setup()
{
  Serial.begin(9600);
  mySerial.begin(9600);
      while (!Serial)
       {
        ;
       }
  Serial.println("Goodnight moon!");
  mySerial.println("Hello, world?");
}

void loop()
{
    if (mySerial.available())
    {
    Serial.write(mySerial.read());
   }
  if (Serial.available())
  {
    mySerial.write(Serial.read());
  }
}