Argentina’s most widely-spoken language is Spanish, but “Spanish” isn’t only just “Spanish.” Argentine Spanish is also known as Castellano, and the most prevalent dialect is “Rioplatense,” which is spoken mainly in the Rio de la Plata basin, along the border with Uruguay, but Argentina’s most particular version of Spanish is Lunfardo, a bawdy regional slang (learn about this very “adult” slang here). Linguists who have studied Lunfardo suggest that Italian immigrants to Argentina, specifically those from Southern Italy, had the most influence on it, and that the Lunfardo accent is closer to that of Neopolitan Italian than any form of Spanish.
Beyond their own form of Spanish, Argentines speak a surprising variety of other languages–Italian (over 1.5 million speakers), an Italian-Spanish mix known as cocoliche, Portuguese, Arabic (about 1 million speakers), German (and a mixture of Spanish and German called Belgranodeutsch), Welsh, a mixture of Welsh and Spanish called Patagonian Welsh, Yiddish (over 100,000 speakers, including a soon-to-be extinct set of “Jewish gauchos”), French, as well as Chinese and Korean. Some communities of indigenous people in Argentina still speak their own languages, such as Guaraní and the Argentine form of Quechua known as Quichua Santiageño. If you ever go to Argentina, certainly haul along that trusty old Spanish phrasebook and use it to introduce yourself to Argentines all over the country, but be prepared to meet people who have much more to say in return.