The adverb is also called a adjective or epithet. It usually describes how an action takes place, for example in the sentence: "The dog is playing funny. The question here is how he plays."
The adverb thus describes the verb in more detail. In German, the adverb does not change. One says: "The boy works attentively" or "The girls work attentively". In the Latin languages, the adverb changes according to the person who is acting.
The adverb can be used in the same way as the adjective: the layman works "cleanly", the expert works "more cleanly", the master works "most cleanly". You can also look for opposites: clean - dirty, light - dark, wet - dry and so on. However, you can hardly find an opposite to many adverbs. Examples are grey, golden, mediocre and others.
It is quite difficult to distinguish between adverb and adjective. It depends on how and where it is in the sentence. In the sentence "I got a droll dog", "droll" is an adjective because it belongs to the noun "dog". But if you say, "The dog plays drolly", then "drolly" is an adverb because it belongs to the verb "plays". Because this distinction is so difficult, it is usually not made at all in the first years of school, but both are called adjectives. This can be both an adverb and an adjective.