This is the 135th most frequent Catalan word.
bona
"Good."
'Bona' is used here as an adjective qualifying the noun 'idea', meaning 'good'.
És una bona idea anar a passejar.
It's a good idea to go for a walk.
'Bona' here acts as an adjective describing the skill level of 'amiga' in storytelling, meaning 'talented' or 'skilled'.
La meva amiga és molt bona explicant històries.
My friend is very good at telling stories.
'Bona' is an adjective modifying 'temperatura', indicating a pleasant or favorable condition.