A more thorough explanation:

A week is a period of seven consecutive days that can begin on either Sunday or Monday. It is also used to refer to any consecutive seven-day period.

For example, if someone says "I'll see you next week," they mean they will see you within the next seven days. Another example is when a work schedule is from Monday to Friday, it is a five-day workweek.

In feudal times, there was an obligation for a tenant to work two to four days in every week for their lord during most of the year, and four or five days during the summer months. This obligation was known as week-work or villein service.

Overall, a week is a unit of time that is commonly used in everyday life and has various applications.