A more thorough explanation:

A treasury is a place or building where wealth is stored, especially a place where public revenues are deposited and kept. It is also the name of a government department responsible for managing a country's finances.

• The United States Treasury is responsible for collecting taxes and managing the country's finances.
• The British Treasury is responsible for managing the country's economy and finances.

These examples illustrate how the treasury is a place where money is collected and managed by the government. The treasury is responsible for ensuring that there is enough money to pay for government expenses and to fund public services.