Bulls: a term given to traders who want to buy and seek to rise in a certain pair of currencies or other commodities, and they are called by this name because they are pushing the price up.
Bears: a term given to traders who want to sell and seek to drop a certain pair of currencies or other commodities.
The credit for the entry of bulls and bears into the forex market is attributed to the Spanish writer Don José de Lavega, who drew that name from the fighting of bulls and Mexican bears. Bears attack bulls from top to bottom, so in the forex market we say that bears push the markets down.
The term bulls and bears were used by traders in global markets to indicate the intense competition in the market that ends in favor of one of the parties buying or selling.