The Present Versus the Future or the Preterite
You can use the present tense in Portuguese to denote a future event. For example, we might say Eu vou ao banco (I go to the bank) when you mean that you will in the near future, say the next day or in a couple of hours. It does not mean that “you always go to the bank,” as the present tense usually means; that is, the present tense is not used to describe habitual actions. Here is a dialogue where speakers use the present tense to denote the future:
Q: Você vai amanhã para Brasília? (You go tomorrow to Brasília?)
A: Sim, a gente sai às duas da tarde. (Yes, we leave at two in the afternoon.)
Q: E quando vocês voltam? (And when do you (pl.) come back?)
A: Nós voltamos na semana que vem. (We come back next week.)
Q: Que legal, aproveitem! (Great, enjoy!)
A: Nós vamos sim! (Yes, we will!)
Notice that this is also the same in English, in other words, the present tense can also be used with future meaning. The big difference between English and Portuguese has to do with the present progressive.
In English you can say “I'm leaving” to express an action in the future, as in “I'm leaving to Rio next month.” But in Portuguese we could not use the presente contínuo to mean something in the future. We would have to use the future tense, and say either Eu vou viajar para o Rio no mês que vem (I'm going to travel to Rio next month) or Eu viajarei para o Rio no mês que vem (I will travel to Rio next month). But if you say Eu estou viajando para o Rio (I'm traveling to Rio) that means you are actually sitting on the plane talking to someone about what you are doing at that very moment!
What are the other uses of the present? One is common in historical texts. It is possible to read a sentence such as Naquele momento D. Pedro grita: ‘Independência ou Morte!’ (At that moment, D. Pedro cries out “Independence or Death!”). This sentence reveals a historical fact that happened in the early history of Brazil, when the son of the King of Portugal took sides and decided to fight for Brazilian independence. That is called the “historical present,” and you might encounter it instead of the regular past tense — another similarity to English!