An idiom meaning being quick to act and adaptable; proactive and mobile in approach (often used casually).
彼女はフットワークが軽いので、急な頼みにもすぐ対応してくれる。
She's quick on her feet, so she responds immediately even to sudden requests.
営業担当はフットワークが軽い人が向いていると言われる。
It's said that people who are quick to move are suited to sales roles.
週末もフットワークが軽くて、友達の誘いにすぐ乗ってしまう。
Even on weekends, I'm quick to go out and often accept friends' invitations right away.