Spanish is the main language here in Argentina. Here it's called castellano instead of español after the Spanish region of Castile where it originated. The language is the same in Spain, Mexico etc - except that it's not. The Argentinian and the Uruguayan accent are famous for the "ssh" sound for ll and y. So my name is - yo me llamo is pronounced in Mexico jo me jamo but in Argentina ssho me sshamo. It's charasteristic especially for the Buenos Aires accent. Here in Cordoba the tone is more singing and the "ssh" isn't as common.
Apart from general oddities in verb conjugation, one speciality is the second person singular pronoun (you) that is vos in stead of tú, so you say - tú dices - vos decís. Like in most Latin American countries, the second person plural pronoun (you, pl.) is not vosotros like in Spain. Instead it's the third person plural pronoun (they) that is ustedes, so you speak - vosotros habláis - ustedes hablan. The conjugation of verbs follows this rule as well and I love it!
There's an excellent song on Youtube about the differences of Spanish in different countries called Qué difícil es hablar el español (How difficult it is to speak Spanish). It makes fun of the different meanings of words in Spain and different parts of Latin America. After two weeks in Argentina, I was completely ready to sign that statement. I've had to change my vocabulary a great great deal here because the people simply didn't understand me when I was talking about shoes, fruits, clothes, kitchen items etc etc etc. So speaking Spanish in one country doesn't mean you are understood everywhere. It's like the Swedish in Finland or the French in Canada sometimes. The language needs to be adapted.
My accent has been doing cartwheels here. The language I speak has been developed through studies in Finland, living in Mexico, speaking with Spanish people in Finland and now living here. When I arrived, I was told I have a Mexican accent. One month later my accent was supposedly Spanish. Now quite a few people unknowing of eachother have said a have a Guatemalan accent. Say what?!?! Well that was unexpected. I knew my accent would change and become a weird mixture of Mexican and Argentinian but this?
Spanish is easy to get started with but difficult to master completely. My Spanish is quite good already, I don't have to make an effort to understand or to speak but I do still fail a great deal on articles, choises of words and in general ways of saying things. Improving by the day. So even if you only know how to say Una cerveza, por favor you're doing good. Speaking Spanish is fun! You should try it!