Thanks for posting your question. I am an Excel user like you.
The issue is that Excel doesn't recognize this as a date so we will have to convert it to a date value first before we can format it. Assuming that the data is always in the same format (yyyy-mm-dd) and you are extracting this to another column, put this formula in the other column:
=DATEVALUE(LEFT(A1,10))
(A1 would be replaced with the cell your data is in) and then format the date any way you want it to show. The month, September, in your example would be a custom format: mmmm as in:
You can drag the formula down and as new data is entered or replaced, the formula will extract the date from it. Make sure that all of the cells where you drag the formula are formatted according to the date format you choose.
Reply again if you have any additional questions. Please mark as answered if this solves your question.
Rich~M