Learn Portuguese (Portugal): O queijo é mau.

Mau means 'bad' for masculine words. Since queijo (cheese) is a masculine noun, the adjective must match its gender. If we were describing a feminine noun, like an apple (uma maçã), we would use the feminine form: A maçã é má.

Why use é instead of está in this sentence?

We use é (from the verb ser) for permanent or inherent characteristics. Saying O queijo é mau means this specific cheese is naturally bad-tasting or of poor quality. If you meant the cheese was fine before but has now spoiled (a temporary state), you would use the verb estar: O queijo está mau.

Since this lesson is about adjective placement, where would mau go if we just wanted to say 'the bad cheese'?

In Portuguese, adjectives usually come immediately after the noun they describe. To say 'the bad cheese' as a single phrase without a verb, you would typically say o queijo mau. In our main sentence, however, mau is describing the cheese across the verb é, exactly like in English.

What is the difference between mau and mal?