Learning some Portuguese before you go to Brazil is an extremely good idea. Although many well-educated Brazilians speak English, and it’s now the main second language taught in schools, this hasn’t filtered through to most of the population. If you know Spanish you’re halfway there: there are obvious similarities in the grammar and vocabulary, so you should be able to make yourself understood if you speak slowly, and reading won’t present you with too many problems. However, Portuguese pronunciation is utterly different and much less straightforward than Spanish, so unless you take the trouble to learn a bit about it you won’t have a clue what Brazilians are talking about. And contrary to what you might expect, very few Brazilians speak Spanish themselves.
Unfortunately, far too many people – especially Spanish-speakers – are put off going to Brazil precisely by the language, but in reality this should be one of your main reasons for going. Brazilian Portuguese is a colourful, sensual language full of wonderfully rude and exotic vowel sounds, swooping intonation and hilarious idiomatic expressions. You’ll also find that Brazilians will greatly appreciate even your most rudimentary efforts, and every small improvement in your Portuguese will make your stay in Brazil ten times more enjoyable.
People who have learned their Portuguese in Portugal or in Lusophone Africa won’t have any real problems with the language in Brazil, but there are some quite big differences. There are many variations in vocabulary, and Brazilians take more liberties with the language, but the most notable differences are in pronunciation: Brazilian Portuguese is spoken more slowly and clearly; the neutral vowels so characteristic of European Portuguese tend to be sounded in full; in much of Brazil outside Rio the slushy “sh” sound doesn’t exist; and the “de” and “te” endings of words like cidade and diferente are palatalized so they end up sounding like “sidadgee” and “djiferentchee”.