function setup(){
createCanvas(600,600);
background(20);
}
function draw(){
for(let x=25;x<height;x+=50){
for(let y=25;y<height;y+=50){
fill(255,120,25,14);
ellipse(x,y,50,50);
}
}
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.1.9/p5.min.js"></script>