Interviewers want to hear that you have experience teaching or mentoring other employees one-on-one. You may have taught a new hire all of your department's standard processes. Perhaps you taught a long-standing employee how to use Excel. You may have mentored an employee who was struggling to hit their monthly goals. All of these scenarios are great examples to draw on. Better yet, if you have personally seen someone struggling with workplace skills or knowledge, approached them, and offered to mentor them, it is a shining example of leadership!
Whatever your scenario may be, tell the interviewer what you helped the person with, while highlighting the positive outcome of their skills improvement.