I want to enable drill down option for KPI Visual Card but i am not able to do it . Please tell me how to do it?

Do you mean that you want to be able to click on the KPI card to view the underlying details?

One way to do this is to create a visual (e.g. a table) for your details and put it in a separate sheet. Create an action for your KPI card, set the action type to “Navigation action” and select the sheet that contains the details as your target sheet.