The picture may say "Fine Semolina" (it was the only type they had at my local supermarket on the day - thanks to the wonders of Brexit!), but if you are going to use any sort for your pizza base, use coarse. It gives the crust another dimension in texture.
What is semolina, also know as "heart of wheat"? It's the part of the wheat grain with the highest protein count. It's been used in milk puddings, Indian halwa, and even for giving roast spuds an extra-crunchy skin.