This is the 3456th most frequent Japanese word.
用事
Task; errand; business.
用事 is used here to mean a task or errand that requires attention.
今日は用事があって、早めに帰ります。
I have an errand to run today, so I'll leave early.
用事 conveys the idea of appointments or tasks scheduled for the weekend.
この週末は用事がたくさんあります。
I have many things to do this weekend.
用事 here refers to errands or tasks, suggesting the completion of responsibilities.