This is the 204th most frequent Spanish word.
buena
"Buena" means "good" in English.
The word 'buena' here is an adjective describing 'amiga' (friend), indicating that she possesses admirable qualities.
Ella es una buena amiga de todos.
She is a good friend to everyone.
In this context, 'buena' functions as an adjective to qualify 'idea', signifying that the idea has value or merit.
Tu idea es muy buena y merece consideración.
Your idea is very good and deserves consideration.
Here, 'buena' describes 'comida' (meal), emphasizing that the meal was enjoyable or of high quality.