Here's why:
* It modifies a verb, adjective, or another adverb. For example:
* "He arrived surprisingly early." (modifies the verb "arrived")
* "The movie was surprisingly good." (modifies the adjective "good")
* "She spoke surprisingly quickly." (modifies the adverb "quickly")
* It describes how, when, or to what extent something happens.
Let me know if you'd like more examples!