If you have sensitive data you'd like to keep from prying eyes in a Microsoft Excel file, the easiest way to protect it is with Excel's built-in password tools.

Fortunately, Excel provides built-in features that allow you to hide and password-protect your worksheets without requiring any programming skills. Password Protecting Excel Spreadsheet Data ...

At the file level, you can password protect an Excel workbook in two ways: You can determine who can get in and who can save changes.

Open the spreadsheet you want to protect in Excel, click the "Review" tab and then click "Protect Sheet" in the Changes group to display the Protect Sheet dialog.