one's leisure hours; free time
Often used adverbially as 暇々に meaning 'in one's spare time' or 'when one has free time'. Can also be used as a noun referring to leisure hours.
I enjoy reading in my spare time.
He goes fishing whenever he finds some free time.
Alternate spelling without the repetition mark; less common but still used.
Reduplication of 暇 (ひま, 'free time, leisure') for emphasis, meaning 'spare moments' or 'leisure hours'.