'calmly' is an adverb that is used to describe how an action is being or was done, often to suggest that an action was done in a tranquil state, without agitation or excess emotion.
1. I calmly walked towards the door.
2. He responded calmly and logically.
3. She calmly discussed the situation.
as the adverb 'calmly' is used to describe a feeling or emotion, it can sometimes be replaced with other adverbs that also suggest tranquility and peace such as 'peacefully' or 'serenely'.