Learn Portuguese (Portugal): O homem é forte, mas trabalha pouco.

In this sentence, pouco (little/not much) is an adverb describing the verb trabalha (works). Adverbs of degree like muito and pouco are invariable when they modify a verb, meaning they never change to feminine or plural forms. It stays exactly as pouco regardless of who is working.

Would the word forte change if we were talking about a woman?

No, it stays exactly the same. Adjectives that end in the letter -e (like forte, grande, or inteligente) are generally used for both masculine and feminine nouns. So, 'the woman is strong' is simply A mulher é forte.

Why do we use é instead of está for 'is'?

We use é, which comes from the verb ser, to describe permanent or essential characteristics. Here, being strong is seen as a lasting physical trait of the man. If you used está (from the verb estar), it would imply he is only temporarily feeling strong at this exact moment.

Why is there no word for 'he' before trabalha?

In Portuguese, it is very common to drop the subject pronoun (like ele for 'he') when it is already clear from the context. We just established we are talking about O homem (the man), and the verb form trabalha already points to a third-person subject, so adding ele is unnecessary.