In this sentence, 'beautiful' is the modified word.

In Japanese grammar, a 'renyou shuushokugo' is a part of 'yougen'.

They (referring to women or girls) are my best friends.

In Japanese grammar, the attributive form is a form that modifies nouns and adjectives.

In Japanese grammar, the adnominal case is the form where nouns or pronouns modify other nouns.

He can speak Japanese fluently.

He is good at speaking Spanish.

He likes to learn new words.

He understands the meaning of the proverb 'Teaching is half learning', which means that teaching leads to one's own learning.

He always keeps in mind the phrase 'If one learns without thinking, it is a waste.'