Translation:Is the wind weak?
The い form is the main present tense adjective. E.g. よわい "weak". This 'i' ending becomes 'ku' when changing to a negative, such as よわくない "not weak" (which, in itself, is an い-adjective). It also becomes 'ku' when you use it as an adverb, e.g. よわく "weakly" (followed by a verb).
There are two types of adjectives in 日本語。い adjectives (like おいしい or よわい) and な adjectives (like きれいな) if you say something is delicious the you say it is おいしい and you use the word in its normal format. Same as きれいな. When the adjective is not the focus of the sentence you will drop the い or な. An いadjective also needs to add a く after dropping the い。 So きれいな becomes きれい じゃ ない and おいしい becomes おいしくない. The word itself never changes is meaning but only allows us to use it in different parts of a sentence.