Exchange rates are reference points, not offers. This guide explains the forces behind the numbers you see.
The Role of Foreign Exchange Reserves
Foreign exchange reserves are assets held on balance sheets by central banks in foreign currencies (primarily USD, EUR, JPY, GBP) and gold to back liabilities and influence monetary policy.
During balance-of-payment crises or currency panics, central banks deploy FX reserves to defend national exchange rates from rapid devaluation.