Adverbs are words that modify verbs by providing information about the manner, place, time, frequency, or other circumstances of the activity denoted by the verb. Adverbs of manner describe how something is done, such as "slowly" or "neatly". Adverbs of place indicate where something occurs, like "around" or "towards". Adverbs of frequency show how often something takes place, such as "twice a day" or "always". The document provides examples of different types of adverbs and exercises to identify adverbs and their categories in sentences.