This is the 723rd most frequent Finnish word.
hyvän
"Hyvän" is the genitive singular form of "hyvä," meaning "good" or "of good" in English.
Here, 'hyvän' is the singular accusative form of the adjective 'hyvä', modifying 'neuvon' (advice). It describes the quality of the advice given.
Annoin ystävälleni hyvän neuvon.
I gave my friend good advice.
In this sentence, 'hyvän' describes the noun 'paikan' (place) and expresses its positive quality.
Hän löysi hyvän paikan istua.
He found a good place to sit.
Hyvän is the genitive singular form of the adjective hyvä, modifying 'sään' meaning 'weather', describing its good quality.