Learn Portuguese (Portugal): Eu falo português e tu falas inglês. - I speak Portuguese and you speak English.

In Portuguese, the names of languages, nationalities, days of the week, and months are written in lowercase unless they appear at the very beginning of a sentence.

Do I always need to include the pronouns Eu (I) and tu (you)?

No, you can easily drop them and just say falo português e falas inglês. Because the verb endings already tell the listener exactly who is doing the action, the pronouns are optional. We often include them for emphasis or to show contrast between two people, which is exactly what this sentence is doing!

Why is it falo for me but falas for you?

Portuguese verbs change their endings depending on who is doing the action. For regular verbs ending in -ar like falar (to speak), the form for 'I' ends in -o (falo) and the form for the informal 'you' ends in -as (falas).

When should I use tu to mean 'you'?

tu is the informal 'you' in Portugal. You use it with friends, family, children, and people your own age in casual settings. If you are speaking to a stranger, a boss, or someone older, you would use a more formal way of speaking, which changes the verb to fala instead of falas.