A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Let's say the birth dates are in B2:B50.
Select this range, then select Format | Conditional Formatting...
Select Formula Is from the first dropdown, then enter the following formula in the box next to it:
=AND(DATE(YEAR(TODAY()),MONTH(B2),DAY(B2))>TODAY(),DATE(YEAR(TODAY()),MONTH(B2),DAY(B2))<=TODAY()+10)
Here, B2 is the active cell within the selected range.
Click Format... and specify the desired formatting.
Click OK twice.