What is the verb of loudly?

"Loudly" is an adverb, not a verb. It describes how an action is performed, but it doesn't describe an action itself.

To find the verb, you need to look for the action word in a sentence containing "loudly." For example:

* He shouted loudly. (The verb is "shouted")

* The music played loudly. (The verb is "played")

Let me know if you'd like more examples!