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.
Variant using numeral 1; common in informal writing.
Combination of もう (more, another) and 一人 (one person).