Mocha coffee (or mocha java) is an arabica coffee grown near the seaport of Mocha, Yemen (thus the name). This coffee is known for its undertones of chocolate, although it does not have any actual chocolate in it.
Mocha, used by itself for the name of a beverage, usually means a beverage made with coffee and cocoa. The word is also sometimes used to describe something with the flavor of coffee and chocolate (e.g. mocha ice cream).
Mocha is the seaport of Yemen originally famous as the source of coffee.
Mocha is also the name of a rapper.