One symbol, many currencies
Several currencies share the same sign. The $ is used for the US, Canadian, Australian and many other dollars, as well as the Mexican peso, so writers often add a code like US$ or CA$ to avoid confusion. The ¥ sign represents both the Japanese yen and the Chinese yuan, and the £ covers the British pound along with a few other pounds.
Historic and newer signs
Some symbols here belong to currencies that no longer circulate, such as the French franc ₣, the Italian lira ₤ and the Spanish peseta ₧, which can be useful for history or collecting. Others are relatively recent additions to Unicode, including the Russian ruble ₽, the Georgian lari ₾ and the bitcoin sign ₿, so very old devices may not display them.