If you need to get the day name (i.e. Monday, Tuesday, etc.) from a date, there are several options depending on your needs.
Do you want to convert the date into a day name?
If you want to convert the date value to a...

In the image shown, the current date is August 24, 2019.
Excel dates are serial numbers, so they can be manipulated with simple math operations. The TODAY function always returns the current date.
Inside the AND...

Note: This example assumes the start date will be provided as the first of the month. See below for a formula that will dynamically return the first day of the current month.
With the layout of grid as shown, the main...

First, this formula determines the first day of the next month *after* a given date. It does this my using EOMONTH to get the last day of the month, then adding one day:
=EOMONTH(B5,0)+1
Next, the formula calculates...

The WEEKDAY function returns a number, 1-7, that corresponds to particular days of the week. By default, WEEKDAY assumes a Sunday-based week, and assigns 1 to Sunday, 2 to Monday, and so on, with 7 assigned to Saturday...

In Excel, the concept of "weekday" or "day of week" is based on the idea that each day of of the week has a specific number. With default settings, the WEEKDAY function treats Sunday as the first day of the week (1),...

At the core, this formula uses the WEEKDAY function to test a number of dates to see if they land on a given day of week (dow) and the SUMPRODUCT function to tally up the total.
When given a date, WEEKDAY simply...

You might wonder why we aren't using the SUMIF or SUMIFS function? These appear to be an obvious way to sum by the days of the week. However, without adding a helper column with a weekday value, there is no way to...

Imagine you have any random date and want find the Monday of the week in which the date appears. You can see you will need to "roll back" a specific number of days, depending on what day of the week the given date is....

The key to this approach is the calendar header (row 4), which is just a series of valid dates, formatted with the custom number format "d". With a hardcoded date in D4, you can use =D4+1 to populate the calendar....

You might wonder why we aren't using COUNTIF or COUNTIFs? These functions seem like the obvious solution. However, without adding a helper column that contains a weekday value, there is no way to create a criteria for...

This formula uses the WEEKDAY function to test dates for either a Saturday or Sunday. When given a date, WEEKDAY returns a number 1-7, for each day of the week. In it's standard configuration, Saturday = 7 and Sunday...

The WORKDAY.INTL function is normally used to generate dates that are workdays. For example, you can use WORKDAY.INTL to find the next workday that is not a weekend or holiday, or the first workday 10 days from now....

Working from the inside-out, the WEEKDAY function takes a date and returns a number between 1 and 7. With default settings, the number 1 corresponds to Sunday and the number 7 corresponds to Saturday.
The CHOOSE...

At the core, this formula uses the WEEKDAY function to figure out the day of week (i.e. Monday, Tuesday, etc.) for every day between the two given dates. WEEKDAY returns a number between 1 and 7. With default settings...