When you say "valuable", do you mean that the nominal exchange rate of a country's currency against foreign currency (the exchange rate listed by banks) is relatively high?

In fact, nominal exchange rate = real exchange rate * foreign commodity price/domestic commodity price.

In the above formula, foreign commodity prices are measured in foreign currency, and domestic commodity prices are measured in local currency, while the real exchange rate refers to the exchange ratio of commodities between the two countries (for example, 2 units of China commodity exchange 1 unit of American goods, and the real exchange rate of RMB against the US dollar is 0.5).

Therefore, we can say that whether a country's currency is "valuable" is directly proportional to the value of domestic goods [international market prices], inversely proportional to the domestic price level, and directly proportional to the foreign price level.

The reason why the pound is valuable is that the comprehensive price index of goods produced in Britain is relatively high in the international market, while the price level in Britain is relatively low.

The exception is that we can see some very special phenomena. For example, the prices of goods in Japan and South Korea are high, but the value of Japanese yen and Korean won is very small. Why? This is because the domestic relative prices of Japan and South Korea are high in local currency.