The EDATE function moves forward or backwards in time in one-month increments from a given start date. The SEQUENCE function is a dynamic array function that can generate multiple results that "spill" onto the worksheet in a "spill range".
SEQUENCE can generate results in rows, columns, or both. In this case, SEQUENCE is configured to output an array of numbers that is 12 rows by 1 column:
The start is zero, and step value defaults to 1, so SEQUENCE outputs an array like this:
This array is returned to as the months argument inside the EDATE function. EDATE then returns 12 dates, beginning with the date in B5. Excel dates are stored as serial numbers, so the output looks like this:
When these results are formatted as dates, the result is 12 dates incremented by one month, beginning May 1, 2019.
End of month
To generate a series of "end of month" dates, you use the EOMONTH function instead of EDATE. The formula in F5 is:
Month names only
To generate a list of twelve month names starting from the current month you can wrap the formulas above in the TEXT function:
Alter the start date to start month names in a different month. For example, to start names in January, use the DATE function to supply an arbitrary January date:
Any January date will achieve the same result, since EDATE will create dates in the next 12 months, and TEXT will convert these dates into month names. The TEXT function uses custom number formats to convert numbers into text. Read more on custom number formats here.