The counter is a number you can use
Last lesson the circles piled up in one spot because we drew them all at the same x. But i changes every pass — 0, 1, 2, 3, 4 — so we can do math with it to move each shape.
If x = i * 40, then the circles land at 0, 40, 80, 120, 160 — neatly spaced 40 pixels apart. Multiplying the counter is the key trick:
Why the + 30?
Adding a number shifts everything over so the first circle isn't jammed against the edge. i * 40 sets the spacing; + 30 sets the starting offset.
You can use i in any calculation — for the size, the color, or the position. That's how a few lines of code can draw a whole pattern.