Hi Baiju, the easiest way to do this is to click on the Text mark and edit the text. Then, format the two measures differently.
You can also do this using Measure Names/Values if you'd like. Let me know if you'd like to go into that. Here's some background in case you need it: Measure Names and Measure Values Explained | Tableau Software
Thanks for the reply. But I couldn't able to change the color of the column , by changing text color in the color mark.