Dizer vs. falar
In Portuguese, dizer and falar both relate to communication, but they are not interchangeable. The core difference is that dizer focuses on the content or message being transmitted (what is said), while falar emphasizes the act or manner of speaking (the process of talking).
Dizer
A1The verb dizer translates to to say or to tell. It is used when you are focusing on the specific information, the content of a message, or a direct/indirect quote. Think of it as transmitting a piece of data.
Ele disse que não podia vir à festa.
(He said that he couldn't come to the party.)
O que a sua mãe te disse sobre isso?
(What did your mother tell you about that?)
O professor sempre diz para estudarmos bastante.
(The teacher always tells us to study a lot.)
Ela abriu a porta e disse: 'Pode entrar'.
(She opened the door and said: You can come in.)
Eu não sei o que dizer nesta situação.
(I don't know what to say in this situation.)
As notícias dizem que vai chover amanhã.
(The news says it's going to rain tomorrow.)
Falar
A1The verb falar translates to to speak or to talk. It is used to describe the general act of communication, the ability to speak, the manner of speaking (loudly, quickly), or the language being spoken. It focuses on the action itself, not necessarily the specific words.
Nós precisamos falar sobre nossos planos.
(We need to talk about our plans.)
Meu filho mais novo já começou a falar.
(My youngest son has already started to speak.)
Por favor, você pode falar mais devagar?
(Please, can you speak more slowly?)
Ela fala três idiomas fluentemente.
(She speaks three languages fluently.)
Eu não gosto de falar ao telefone.
(I don't like to talk on the phone.)
Eles estavam falando muito alto no cinema.
(They were talking very loudly in the movie theater.)
Summary
In essence, use dizer when you are reporting what someone said (the message). Use falar when you are referring to the act, ability, or manner of speaking (the action). If you are talking about the what, use dizer. If you are talking about the how or the general action, use falar.