noun, adverb
another person; one more person; the other person
Refers to an additional person or the other person in a pair/group. Often used when counting people or specifying someone else.
もう一人、手伝ってくれる人はいませんか。
Is there one more person who can help?
彼はもう一人の友達を連れてきた。
He brought another friend.
もう一つ means 'one more (thing)', while もう一人 specifically means 'one more person'.
Combination of もう (more, another) and 一人 (one person).