Adverb used to describe the meaning of any parts of speech except noun or pronoun. An adverb therefore can say something about a verb, a adjective or an adverb.
An adverb cannot modify an Interjection. An interjection is not truly a word to participate in the construction of a sentence. It is simply a sound to express some feelings or emotions not related to any other word in the sentence. It is merely an exclamatory sound.
Ex: I caned him mainly because he stole my pen.
Why caned? Because he stole my pen. Only for this reason? No, No, not for that only. I consider it a great offence to steal. It shocked me, so I caned. The word mainly expounds all these reasons contained in the connective because. because is a joining word (= conjunction) between i caned him and he stole my pen. mainly points to because. The word mainly is an adverb.
Describe verb: He walks slowly.
Describe adjective: This is a very beautiful picture.
Describe adverb: This can be done more easily.
Describe preposition: I arrived long before the time.
Describe conjunction: I hate him simply because he is a lier.
Describe sentence: Unfortunately i failed.
Different Kinds of Adverb
Adverb of time: Now,then,when,early,before,daily,ever,never,soon,while,ago,today ,yesterday.
Adverb of place: There where,near,above,after,below.
Adverb of manner: Well,ill,badly,quickly,highly,wisely.
Adverb of quality or number: Almost,enough,much,little,once,very.
Adverb of cause: Therefore,accordingly.
Adverb of affirmation/negation: Yes,no,not,certainly,probably,really.