Hi @shweta,
I assume that you tried to use the visual type KPI to display the result of your calculated field (please let me know if this assumption is inaccurate). The KPI visual works on top of numeric values. If dimensional fields are selected, the COUNT aggregate function is applied to create numeric values. Also in your case, the result of your calculated field is a string and no numeric value and, hence, the visual type KPI does no longer work to visualize the result of it. Instead you could simply use for example visual type Table and remove all header information and non-desired formatting from it to simply display the aggregated value and title within the visual.
I hope my solution worked for you. Let us know if this is resolved. And if it is, please help the community by marking his answer as a “Solution”.