"Skilled" is an adjective that describes the musician as having a high level of proficiency. It modifies the noun "musician" and gives more information about the musician's abilities.

"Flawlessly" is an adverb that describes the way the musician played the piece. It modifies the verb "played" and gives more information about how the musician played the piece. It indicates that the musician played the piece without making any mistakes.

Adjectives are words that describe nouns and adverbs are words that describe verbs, adjectives, or other adverbs. In this sentence, "skilled" describes the noun "musician" and "flawlessly" describes the verb "played" and gives more information about how the musician played the piece.