No, buena can be located in either place. Before the noun, the adjective is either emphatic or figurative. After the noun it is literally what the words indicate. So in this case it is more correctly “great" or “really good", because it emphasizes that she's better than just a “good person". She's good enough to move the adjective!
Thank you for responding. It's interesting to know. I have 5 sisters but we never address each other as "sister" unless we are joking, that's why I was wondering. "Sis" is used rather often, that's also why I wanted to know if there was a shorter version of "hermana" or if it is just used for "sis" too.
"persona" is feminine therefore "buena persona". "buen" drops the "o" when used before masculine singular nouns. "buenos" is used with masculine plural nouns and "buenas" is used with feminine plural nouns. The adjective "bueno" is placed before the noun when used as an opinion and after the noun when descriptive. Some adjectives change meaning when used before or after. For example. Son grandes ciudades. They are great cities. Son ciudades grandes. They are big cities.
Can someone please clarify why the adjective "buena" is placed before "persona" in this sentence? I understand that adjectives go in front of the noun if they quantify the noun but this is not the case. One user suggested that this is because it is an opinion, but then why in the sentence "Mi esposo es un abogado responsable" does the adjective go after the noun? Isn't "responsible lawyer" a subjective and opinion-based case as well?
So I found an article about this. Apparently "bueno" falls into the category of meaning-changing adjectives, where the placement affects the meaning of the word. However, the meaning of "bueno" if it's before the adjective is "simple/good" and if it's after it's "good/gentle/generous". I'm still not really sure I understand! Here's the article http://www.spanishdict.com/guide/adjective-placement