The word "denarii" is the plural of "denarius. "AT: "The amount of bread that cost two hundred days' wages" (See: rc://en/ta/man/translate/translate-bmoney)
"Five loaves of barley bread." Barley was a common grain.
A loaf of bread is a lump of dough that is shaped and baked. These were probably small dense, round loaves.
This remark appears in the form of a question to emphasize that they do not have enough food to feed everyone. AT: "these few loaves and fishes are not enough to feed so many people!" (See: rc://en/ta/man/translate/figs-rquestion)