Four rows. The two end caps are fixed; everything between them is shuffled. Click one cap and then another to swap them, until each row runs smoothly from one end to the other.
This is the arrangement format, which is a real one. Clinical hue-arrangement tests work exactly this way: a run of caps of equal lightness and equal saturation, differing only in hue, which you put back into order. The error is not whether you got it right or wrong — it is how far each cap ended up from where it belongs, added up. Somebody with normal colour vision makes a few small errors spread evenly; a specific weakness shows up as a cluster of large errors in one part of the circle.
The caps are spaced in CIELAB, not in RGB. Stepping evenly through RGB hue gives you caps that are obviously different in some places and nearly identical in others, which measures the colour space rather than your eyes. These are constant in lightness and chroma and evenly spaced in hue angle, with the chroma chosen as the largest one that keeps every cap inside what the screen can actually show — the page says which figure it settled on.
It is not a diagnosis and cannot be one. A real test is done under a standard light source, with real pigment caps, at a fixed distance. This is a screen of unknown calibration in a room of unknown lighting. Take the number as a comparison with your own earlier attempts and nothing more; if you have a real reason to wonder, an optometrist has the real test.