one-on-one; man-to-man
Used for direct, personal interaction between two people, such as teaching, coaching, or a private conversation.
I'm receiving one-on-one English conversation lessons.
I had a chance to talk one-on-one with my boss.
The teacher teaches the student English one-on-one.
He greatly improved his pronunciation through one-on-one guidance.
The coach and the athlete are practicing one-on-one.