Spanish for apple, Manzana (as a proper noun) is also a brand of apple-flavoured soda sold in Mexico and other parts of Latin America. In fact, Manzana (or Manzana LIFT, as it's full name is) is a product of the Coca-Cola Company; while its arch-nemesis Pepsi-Cola makes a similar product called "Manzanita: Sol" (this literally translates as "little apple: sun," although I'm sure the Sol part must be of some connection to Mexican beer company of the same name).
But whatever the case, wheather Manzana LIFT or Manzanita: Sol, both taste very similar and either one can be referred to as simply Manzana. As far as what sort of flavour these beverages actually have; it is somewhat similar to Martinelli's sparkling cider, although with less carbonation and a more intense apple flavour.