How do I connect a temperature and heartbeat sensor to an Arduino Uno?
If you separate your code into functions you may understand what you want to do better.

In the listing above, you have code that reads the temp and prints the temp.  So creating two functions ReadTemp() and ShowTemp() will make the code in loop look cleaner and easier to read.  i.e.

void loop()
{
    const float cel = ReadTemp();
    DisplayTemp(cel);
    delay(1000);
}

float ReadTemp(void)
{ 
    val = analogRead(tempPin);
    float mv = ( val/1024.0)*5000; 
    float cel = mv/10;
    // float farh = (cel*9)/5 + 32;
    return cel;
}
void ShowTemp(const float&amp; cel)
{
    Serial.print("TEMPRATURE = ");
    Serial.print(cel);
    Serial.print("*C");
    Serial.println();
}


In you sketch for the hearbeat monitor you should have some code that reads the heartbeat and some that prints it.  If you create two functions ReadHB() and ShowHB() you will be able to easily add them to the above loop function.

I've never used the serial plotter, but if you wrap it in a function called PlotTemp() and PlotHB() then you can slot them in instead of the Show functions.