SOURCE

let ball;
function setup(){
    createCanvas(500,150);
    background(200);
    ball = new Ball(10,10,20,60,6,5);
}
function draw(){
    ball.move();
    ball.drawing();
}
class Ball{
    constructor(ballX,ballY,ballD,ballColor,ballXSpeed,ballYSpeed){
        this.ballX=ballX;
        this.ballY=ballY;
        this.ballD=ballD;
        this.ballColor=ballColor;
        this.ballXSpeed=ballXSpeed;
        this.ballYSpeed=ballYSPeed;
    }
    move(){
        this.ballX+=this.ballXSpeed;
        if(this.ballX>width-this.ball/2){
            this.ballXSpeed=-this.ballXSpeed;
        }
        else if(this.ballX<this.ballD/2){
            this.ballXSpeed=-this.ballXSpeed;
        }
         this.ballY+=this.ballYSpeed;
        if(this.ballY>height-this.ballD/2){
             this.ballYSpeed=-this.ballYSpeed;
        }
        else if(this.ballY<this.ballD/2){
            this.ballYSpeed=-this.ballYSpeed;
        }
    }
    drawing(){
        push();
        translate(this.ballX,this.ballY);
        fill(this.ballColor);
        ellipse(0,0,this.ballD,this.ballD);
        pop();
    }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.1.9/p5.min.js"></script>