The economy of the United States is the world's largest by nominal gross domestic product (GDP), meaning it has the highest market value of goods and services production output. Despite this fact, the British pound’s nominal value is higher than the US dollar.
The explanation for this is that the nominal value of a country's currency is not necessarily related to its economic strength.
Another example of this can be found in EUR/USD, the world’s heaviest traded currency pair, which has a numerator (EUR) that is nominally higher than the denominator (USD), yet this is not related to the strength of US and European economies.