Learn Portuguese (Portugal): O homem é magro.

Adjectives in Portuguese change to match the noun they describe. Because homem (man) is a masculine noun, the adjective takes its masculine singular form, magro. If we were talking about a woman (a mulher), it would change to magra.

Does magro still have to match homem even though they are separated by the verb é?

Yes! Even when an adjective is separated from its noun by a verb like é (is), it still has to agree in gender and number with the noun it describes. So magro stays masculine and singular to match O homem.

Why do we use é (is) here instead of está?

In Portuguese, we use é (from the verb ser) for permanent or long-term characteristics. Using é means the man is naturally or generally thin. If we used está (from the verb estar), it would imply he is only temporarily thin, perhaps because he recently lost a lot of weight.

Why is the 'h' in homem completely silent?

In Portuguese, the letter 'h' at the very beginning of a word never makes a sound. You pronounce homem as if it started directly with the letter 'o'.