The interviewer wants to know the attributes that you value most in a team leader. List a few attributes that you feel are most valuable for a team leader to possess and be sure to comment on how those relate to your strengths. Good examples might include: Trustworthy - Accountable - Committed - Results-oriented - Detailed - Driven - Strong Negotiator - Reliable.
All of these attributes are valuable in a team setting, and any of them will make sound examples for you.
"I feel that a strong team lead should be motivating, competitive, and a natural mentor. I have had leaders with these qualities, and it makes any team project run much smoother when they possess these. When I lead a team, I do my best to emulate these qualities as well."