[xwowsersx]

I think the idea is this:

1. On the left under "Dates" are the consecutive days of the month if you read column by column (of course not every month has 31 days).

2. The rows represent intervals of a week (hence each square is previous + 7).

3. Look first at the top left cell with June and Monday. That lines up with the days of the month 1, 8, 15, 22, 29. That's because those are all the Mondays of June.

4. Next row (same column) shows similar: The Tuesdays of June are 2, 9, 16, etc.

So you can start with any month (the columns) and look at the first row underneath to see which day of the week the month starts on and then follow the dates from there using the above logic.