Question

When money is used to express the value of goods and services, it is functioning as a?

Answer 1

Unit of account. The unit of account is used in economics to measure currency that is being used to represent the real value or cost of an economic item. These items can be goods, services, assets, liabilities, income and/or expenses. Units of account is one of the three well-known functions of money.

Answer 2

The term money is used to describe anything that is regularly used in economic transactions or exchanges.
When money is used to express the value of goods and services, it is functioning as a unit of account.
This is the primary function of money, to be used a unit by which value of a thing is accounted and compared.