To convert an Excel file to CSV (Comma Separated Value) format, you can use the following steps:

• Open your Excel file in Microsoft Excel.
• Select "Save As" from the "File" menu.
• Choose "CSV (Comma delimited) (*.csv)" from the "Save as type" dropdown menu.
• Choose the location where you want to save the CSV file.
• Click on the "Save." button.
• If prompted, click "OK" to confirm that you want to save the file in CSV format.
• If any warning message appears, click "Yes" to continue.

Alternatively, you can also use the third-party Cigati Excel to vCard Converter to export excel files to CSV file format with no data loss. Also, it can convert your Excel xls, xlsx files to vCard, Text, and CSV format with ease.