One of the eight parts of speech, adjectives are a type of modifier. They serve the same purpose in French and English, but they are very different in two respects.
There are six French adjective / pronoun pairs, where an adjective + noun can be replaced by a corresponding pronoun.
When describing someone as capable of doing or determined to do something, a preposition is required between the adjective and verb. In French, the choice of preposition depends on the adjective that precedes it, not the verb that follows.
Adverbs of manner express how the action of a verb occurs. In English, the vast majority of adverbs of manner end in -ly, whereas in French, they mostly end in -ment. They are created from adjectives.
The three French verb constructions which include some form of être plus a past participle usually require grammatical agreement of the past participle with the subject.
Ce, cette, cet, and ces are demonstrative adjectives, which are used to indicate a specific noun or nouns. In French, they must agree with the noun(s) in number and sometimes gender.
French grammar is sometimes trumped by pronunciation, as in the case of euphonic adjectives. Because French does not like the hiatus created when a word ending with a vowel precedes a word that begins with a vowel or mute h, a few adjectives change their spelling—and thus their pronunciation—for purely euphonic reasons.
To express admiration, surprise, contempt, or another strong feeling about a noun, you can use the exclamative adjective quel, meaning "what (a)."
Indefinite adjectives like certains, divers, and quelques describe nouns in a general or non-specific way. Many indefinite adjectives indicate a vague quantity.
With articles, the de vs du, de la, des choice has to do with affirmative/negative and whether there's an adjective in front of the noun.
When asking someone to make a choice between two or more things, you need the interrogative adjective quel, meaning "which" or "what."
Relative pronouns are rare in both French and English, as they are found primarily in legal, administrative, and other very formal language. The French relative pronoun lequel creates a link between a preceding antecedent and a following noun.
A number of French adjectives change meaning depending on whether they go before or after the noun.