Learn Portuguese (Portugal): Ela tem bom feitio.

In Portuguese, certain personal characteristics like temperament, charm, or luck are expressed as things you "have" rather than what you "are". Instead of saying someone is good-natured, you say they have a good nature (ter bom feitio). You'll also see this with phrases like ter sorte (to be lucky).

What does the word feitio actually mean?

Feitio literally refers to the "make", "shape", or "workmanship" of a physical object, like a piece of clothing. When applied to a person, it metaphorically refers to the "shape" of their personality—their character, temper, or disposition.

Normally adjectives come after the noun in Portuguese. Why is it bom feitio instead of feitio bom?

While most adjectives do come after the noun, a few short, common adjectives like bom (good) and mau (bad) frequently come before it. Placing bom before the noun also highlights that this is an inherent, fundamental trait of her personality rather than just a passing mood.

How would I say the exact opposite, that someone is bad-tempered?

You would simply swap bom for mau (bad). The phrase ter mau feitio is a very common everyday expression in Portugal to describe someone who is grumpy, difficult to deal with, or has a short temper.