Making negative statements in Portuguese is fairly easy. For the most part, to make a sentence negative, you can just place the word não before the verb, which is the equivalent of both no and not. Examples:
Este carro é rápido. This car is fast.
Este carro não é rápido. This car is not fast.
Não is also used at the beginning of sentences, when replying to a question:
Queres água? Would you like some water?
Não, obrigado. No, thank you.
But there are also three other words that express negation in Portuguese – nada, ninguém, and nenhum/nenhuma. Their use depends on the subject or object of the sentence.
Nada is the equivalent of “nothing”. It is only used for things or abstract concepts, and it is pretty straightforward for English speakers. Example:
Nada mudou desde o ano passado. Nothing changed since last year.
Nenhum/nenhuma are, respectively, the masculine and feminine equivalents to “none”. They’re used for both objects and people. Example:
Nenhum dos convidados trouxe comida. None of the guests brought food.
Nenhuma destas camisas me serve. None of these shirts fit me.
Unlike nada and ninguém, which are always the same (i.e. invariable), nenhum/nenhuma have a plural form: nenhuns/nenhumas, which is roughly equivalent to the English word “any” when “any” is paired with a negative. Examples:
Não vi canetas nenhumas! I didn’t see any pens!
Não ouvi cães nenhuns! I didn’t hear any dogs!
From these examples, you can see that this plural form is usually employed when you want to answer questions emphatically. In this case, with “não” at the start of the sentence, the plural form is placed after the noun. Interestingly, unlike English, this double negation is a perfectly acceptable construction in Portuguese. The negatives don’t cancel each other out, but, instead, reinforce each other.