An amount of currency
The hard value of that amount of currency depends on monetary authority of the issuing country.
A person can have twenty:
Australian Dollars - AUD
Hong Kong Dollars - HKD
United States Dollars - USD
Canadian Dollar - CAD
New Zealand Dollar - NZD
Twenty Dollars can buy many peanuts.
Brain: Twenty Dollars can buy many peanuts!
Homer: EXPLAIN HOW! D:
Brain: Money can be exchanged for goods and services.