This is the 8748th most frequent Japanese word.
月曜
Monday.
"月曜" in this sentence indicates the time of an event, specifying that the meeting will be held on Monday.
月曜日に会議があります。
There is a meeting on Monday.
"月曜" is used as a subject in this sentence to refer to Monday being a holiday.
月曜日は学校が休みです。
Monday is a holiday from school.
"月曜" in this sentence serves to define a deadline, specifying a point in time by Monday.