A more thorough explanation:

Excambium is a word that means exchange. It can refer to a place where merchants meet to do business or to something given in return for something else.

• At the excambium, the merchants traded goods and services.
• The company offered an excambium of stock options in exchange for a pay cut.

The first example shows how excambium can refer to a physical location where people exchange goods and services. The second example shows how excambium can refer to something given in return for something else, in this case, stock options given in exchange for a pay cut.