Currency pairs are also known as forex pairs. If you buy a currency pair, you’re buying the base currency and selling the quote currency. The bid (buy price) represents how much of the quote currency you need to buy one unit of the base currency. If you sell the currency pair, you’re selling the base currency and buying the quote currency.
For example, GBP/USD is the currency pair for British pound sterling against the US dollar. If GBP/USD is trading at 1.3740, then 1.3740 dollars will buy you one pound.