How do I generate a value using automation based on a period of time in the calendar column?

Julie0701

Hi I would like to set up a automation to assign a specific number, based on the time period which is set in a different drop-down column.

For example, I would like to have return number "1" in column Period, when my Date of Expense is Jan.

Could someone help me with this? Thank you.

Paul Newcome

What would be the rest of them, and do you need to be able to manually enter data in any of the cells in this column?