noun which may take the genitive case particle 'no', na-adjective
quickly adaptable; proactive; light on one's feet
Slang abbreviation of フットワークが軽い, used especially among young women to describe someone who is quick to act, easygoing, or readily joins activities.
See also: フットワークが軽い
彼女はフッ軽だから、急な誘いにもすぐ来てくれる。
She's so quick to respond that she'll come even to last-minute invitations.
フッ軽な人ほど友達が多いよね。
People who are light on their feet tend to have more friends, don't they?