let sec = 0;

let timer=0;

​

function setup() {

  createCanvas(400, 400);

  colorMode(HSB);

  rectMode(CENTER);

}

​

function draw() {

  background(220);

  fill(c,100,100);

  square(width/2,height/2,100);

  fill(0);

  if(sec != 1){

  text(sec+' seconds',width/2-25,height/2+75);

  }else{

  text(sec+' second',width/2-25,height/2+75);

  }

​

  if(millis()-timer>=1000){

    //every 1 second something happens

    c += 10;

    sec +=1;

    timer=millis();

  }

  if(c>=360){

    c=0;

  }

}