Variables - initialize and assign.

sketch.js

function setup() {
  createCanvas(640, 480);

  // use anti-aliasing
  smooth();

  // no stroke on my shapes
  noStroke();

  /*
    use upper left corner
    not the center
  */
  ellipseMode( CORNER );

  // just run the draw cycle 1 time :)
  noLoop();
}

function draw() {
  background( 247, 250, 248 );

  /*
    this is why we use variables.
    variables can hold a value and we can use
    basic mathematic operations to change the value.
    */
  var x = 20;
  fill( 46,213,101 );
  ellipse( x, 20, 20, 20 );
  console.log( "[example 2] value of x: " + x );

  /*
    when we use '+' or "=" these are called operators
    there are many types of operators and they do
    different things
    */
  x = x + 30;
  fill( 41,49,119 );
  ellipse( x, 20, 20, 20 );
  console.log( "[example 2] value of x: " + x );

  x = x + 30;
  fill( 253,209,60 );
  ellipse( x, 20, 20, 20 );
  console.log( "[example 2] value of x: " + x );

  x = x + 30;
  fill( 174,129,255 );
  ellipse( x, 20, 20, 20 );
  console.log( "[example 2] value of x: " + x );
}