The UpperCase function capitalizes all letters in a string. A good use case is using UpperCase on a coupon code or some value that you want in all uppercase.
%%[ set @couponCode = Uppercase([CouponCode]) ]%% Here is your code: %%=v(@couponCode)=%%,
Here is your code: ADS3G5GFSS
The UpperCase function capitalizes the letters in the string and ignores the numbers. This is helpful if your data is not formatted correctly in the data extension and you want it to show consistently in all capital letters.