Here's why:
* Adverbs modify verbs, adjectives, or other adverbs. "Profoundly" often modifies verbs, describing how an action is done (e.g., "He was profoundly moved by the music."). It can also modify adjectives (e.g., "She had a profoundly insightful perspective.").
* Adverbs often end in -ly. This is a common characteristic of adverbs, though not all adverbs end in -ly.
Let me know if you have any other words you want to analyze!