The current week is displayed above.

It shows the year, halfyear, month, and week.  They are all highlighted in red.  The current day of the week is highlighted in yellow.

The current week changes at 12AM GMT on Sunday every week.

If the month has 4 wednesdays, it is a 4-week month.  If a month has 5 wednesdays, it is a 5-week month in which has what is called a leap week.

There are 7 days in a week.

There are 4 or 5 weeks in a month.

There are 6 months in a halfyear.

There are 2 halfyears in a year.