There are several ways of writing Arabic. It can be done in horizontal lines, starting at the upper right, proceeding to the upper left, going back to the right, starting the next row down. Like the Indo-European writing systems work. Row after row, top to bottom.
The other way is the words, and letter groups, start out anywhere and continue anywhere on the page, or coin, or whatever it is. For example, if the word “Sultan” is at the bottom of the coin, and the guy’s name above it. You start reading by looking down, then you have to look up to get to his name. The lifted eye is a grateful eye. One lifts one’s eyes to Heaven, from which comes one’s Salvation. So, reading the coin “becomes” an act of gratitude and obeisance to the ruler who authorized the coin, the expression of Heaven’s authority on earth.
Letter sets happen in Arabic because some letters can connect to the next letter in a word and some can’t, so a word can consist of two or more letter clusters. Stylistically, a calligrapher might think it affecting, in some way, to put a cluster here, the next cluster there, etc. It might mean something, or allude to something, or conveniently make yet another word with a letter cluster next to it. Scattering the clusters and words all over the coin can make things harder to figure out. Later medieval Central Asian coins can be particularly
