void setup() 
{
  Serial.begin(115200);
  for(int i=1;i<8;i++) // first for loop
  {
    Serial.print("i= ");
    Serial.print(i); 
    Serial.print("  ");

    for(int j=1;j<6;j++) // second for loop inside the 1st for loop (this is called nesting. hence nested for loop)
    {
        Serial.print("j= ");
        Serial.print(j); 
        Serial.print("  ");
      
    }
  Serial.println();
  }
}

void loop() 
{
  //Serial.println("loop"); 
}