In the sentence
質問のある方はどうぞ
what is the meaning of 方?
「質問{しつもん}のある方{かた}はどうぞ。」
「方{かた}」 in this context is the honorific/respectful form of 「人{ひと}」 ("person(s)"). The meaning is the same for both.
"Those who have questions, please (ask)!"
