When using the dropdown menu in the exchange to select a market, there are a number of different options and abbreviations.
The leading currency represents the currency you wish to sell or to purchase. The trailing currency represents the funds with which you wish to perform your action. You are able to place buy and sell orders for different crypto and fiat currencies on the exchange for each other. This allows you to obtain the best price for your trade. Follow this link for more information on placing buy and sell orders on the exchange.
For example, BTC/CAD market option.
This market will provide you with the option to purchase BTC on the exchange with CAD funds. Alternately placing a sell order will exchange your BTC for CAD.