First, create an excel sheet with some dummy data as below image.
Now, Steps are given below
Steps 1: First calculate Current month into current Month column using TODAY function as below
Step 2: Now calculate Employee’s birthday month as below
Step 3: Now check birthday month with current moth. If “Current month” value equal to “Month of Birth” then return yes as alert in “Alert” column as below image
=IF([@[Current Month]]=[@[Month of Birth]],"yes","")