What is this potentiometer for? I am working on an anemometer project using Arduino. I don't know barely anything from Arduino and I am following this tutorial.
I have some doubts on the making part. This is what I have to make: 
and this is the code:
//anemómetro con LCD
#include &lt;LiquidCrystal.h&gt;

LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

float veloc1 = 0; // entrada A0
int tiempo = 0;
int cnt = 0;
float v1 = 0;
float v2 = 0;

void setup() {
  lcd.begin(16, 2); // Fijamos el numero de caracteres y filas
  lcd.begin(16, 2); // Fijamos el numero de caracteres y filas
  lcd.print(&quot;Anemometro EC&quot;); // Aqui va el mensaje
  analogReference(INTERNAL);// pone como referencia interna 1.1V
}

void loop() {
  v1 = (analogRead(0)); // lectura de sensor a0
  veloc1 = (v1 * 0.190); // 0,190 corresponde a la pendiente de la curva aca deben poner el numero que calcularon
  lcd.setCursor(0, 1); // Ponte en la line 1, posicion 0
  lcd.print(veloc1); //muestra la velocidad del viento en el LCD
  lcd.setCursor(4, 1); // ponte en linea 1, posicion 5
  lcd.print(&quot;Km / h&quot;);
  lcd.setCursor(9, 1);
  lcd.print(&quot;Max&quot;);
  if (veloc1 &gt; v2)v2 = veloc1, lcd.print (v2, 1); // muestra la velocidad maxima que alcanzo
  delay(1000);
}


What is the potentiometer doing here? Why is it necessary?
My lcd screen doesn't show anything. Does anyone knows why??

Thanks in advance.
What is the potentiometer doing here? Why is it necessary?

It's there to control the &quot;offset voltage&quot; of the LCD, which is what controls the contrast of the display.

My lcd screen doesn't show anything. Does anyone knows why??

Maybe you wired it wrong. Maybe you didn't put the potentiometer in the circuit because you didn't understand what it is for. Maybe you just need to adjust the contrast by turning said potentiometer. It's hard for us to tell. By showing us what you intended to build and then telling us that what you actually built doesn't work, there is nothing we can tell you. There must be some difference between what you intended to build and what you did build, but we can't see what you built, so we can't have any clue.