A person with specialized skills or knowledge as their profession, and the attitude/responsibility that accompanies it; a loanword used as a noun or na-adjective.
彼はプロフェッショナルな態度で仕事を進める。
He carries out work with a professional attitude.
プロフェッショナルになるには技術だけでなく責任感も必要だ。
To become a professional, you need not only skills but also a sense of responsibility.
彼女はプロフェッショナルとして認められている。
She is recognized as a professional.