An obstacle or impediment that interferes with progress or functioning. Often used in the phrase 'there is/isn't a problem/obstacle'.
ソフトの不具合で作業に支障が出た。
Work was hindered due to a software bug.
明日の予定に支障がなければ、その会議に出席します。
If there are no problems with tomorrow's schedule, I'll attend that meeting.
台風の影響で交通機関に支障が出ている。
Transportation is disrupted due to the typhoon.