This is the 295th most frequent French word.
meilleur
"Meilleur" means "better" or "best" in English.
Here, 'meilleur' functions as a superlative adjective, modifying the noun 'restaurant' to indicate that it is better than all other restaurants in the city.
Ce restaurant est le meilleur de la ville.
This restaurant is the best in the city.
In this sentence, 'meilleure' is the feminine singular form of 'meilleur,' used to agree with the noun (amie) it describes, showing a quality of being superior or better.
Elle est ma meilleure amie.
She is my best friend.
In this case, 'meilleur' is used comparatively to describe the superiority of one action (eating vegetables) over another for health improvement.