Puh.. with side? Good question. Never seen such stone before. I think you will have to try and see if the Stone has different grids. I assume that the yellow one might be the standard side and the other might have been colored.
However, I would always Lapp a used stone when getting it. Take a pencil and draw some diagonal lines all over the stone. Than take a fine whet sanding paper. Lay the paper on a lean surface and Lapp the stone one the sanding paper. Best way is to lead the stone in 8-Stokes (like drawing eights on the sanding paper). After some stokes take a look if the pencil lines are all eliminated. Perhaps the lines will stand to go on the corners of the stone . That’s what usual happens with used stones, because they became a bid concave from the former unse. If so, continue until all pencil lines have gone. Finally make again some lines and make the same procedure wir a finer sanding paper (around 1000 grid). Once all lines have gone you can expect that you have a lapped stone and can put your razor up.
How may stokes you will need is hard to predict. I do not even know if this is really a finishing stone. If your razor is Stil sharp and need only a refresh, make 10 double stokes (alway front one side, back the other side, to be shire that you will not get a burr. Test the Edge on your arm hairs and if you find the feeing sharp and. Smooth, start stropping on a leather strop about 100 double strokes. If the edge is worse than before (more crispy, not keen) the stone is probably not a finisher. If it’s better, continue shaving.