Catalan is a sort of dialect/could be an independant language from Spanish, spoken in Cataluña, an area in eastern Spain; as Paula said, you don't really need to speak it when going to Spain because even in Cataluña they speak Castellano: the official Spanish spoken in Spain. In Latin America, they speak Yéismo, a form of Castellano which is not fundamentally different - just a phonetical difference, with the occasional different nuance as well. What you refer to as Spanish is Castellano, so learn that.