WORKDAY.INTL is a function in Microsoft Excel that calculates the date that is a specified number of workdays (business days) ahead of a given start date, excluding weekends and optional holidays.

The function takes four arguments:

start_date: the initial date from which the calculation is based

num_days: the number of workdays (business days) to add to the start date

[weekend]: an optional argument that specifies the days of the week that are considered weekends. By default, Saturday and Sunday are considered weekends, but the user can customize this by specifying a string of binary digits where 1 represents a weekend day and 0 represents a weekday.

For example, "0000011" would mean that only Friday and Saturday are considered weekends.

[holidays]: an optional range of cells or array of dates that represent holidays that should be excluded from the calculation.

The function returns the date that is numdays workdays after the startdate, excluding any weekends and holidays that have been specified.