Answer:
Ravi quickly <u>reads </u>mystery novels. ⇒⇒ This verb expresses an action.
<em>Read</em> is the verb in this instance that represents the action of reading.
Ravi quickly reads <u>mystery</u> novels. ⇒⇒ This adjective describes a person, place, or thing.
The adjective <em>mystery</em> in this sentence is used to describe the type of novels that Ravi reads.
<u>Ravi </u>quickly reads mystery novels. ⇒⇒ This noun is a person, place, or thing.
<em>Ravi</em> is the name of the person doing the reading here and so is a noun.
Ravi <u>quickly</u> reads mystery novels. ⇒⇒ This adverb describes how an action is completed.
<em>Quickly</em> is the adverbial form of the adjective <em>quick</em> and in this case is being used to describe how Ravi reads the novels.