The term "Afghan monetary unit" refers to the basic unit of currency used in Afghanistan. In simpler terms, it is the money that people in Afghanistan use to buy things, just like how we use dollars in the United States or euros in Europe.
While "Afghan" primarily refers to something from Afghanistan, it can also refer to a type of blanket (often knitted) in English. However, in the context of "Afghan monetary unit," it strictly relates to currency.
There are no specific idioms or phrasal verbs directly related to "Afghan monetary unit," but you might come across phrases like "money talks," which means that money can influence decisions.