noun
ability to take action; initiative; drive
Refers to a person's capacity to act decisively, get things done, and show initiative. Often used in self-improvement, business, and personal character descriptions.
彼は行動力があるので、すぐにプロジェクトを始めた。
He has initiative, so he started the project right away.
To develop the ability to take action, it's good to start with small things.