@Pavani_Regulagedda  could you give more details of which functionality you are using to generate the Excel files?

Are you using MSOGenerateExcelFile?  Can you use pxGenerateExcelFile? 

I found a possible explanation:

In earlier releases every time a possibly vulnerable cell value was found during Export to Excel, the value on that cell was modified to prevent a formula injection attack. If the value was non numeric, it would still render an apostrophe, although it should be hidden. Previous work on this issue involved the addition of a DSS which allowed this security to be disabled if the Excel was going to be consumed by an external tool, but the security implementation used to protect against calculation injection has reworked the ExcelSecurity utility function to allow the ability to change the cell style of a cell that is potentially vulnerable to formula injection attacks. This change no longer changes the cell value but instead applies a new cell style that has quotePrefix enabled. 

In order to avoid calculation injection during Export to Excel, an apostrophe character was added to the cell on export to close a vulnerability. However, sites using an external tool to consume the Excel document needed a workaround for this security feature.

The resolution for this issue adds a DSS setting "TurnOffSecurityForExportToExcel" which can now be used to turn on/off the security feature that adds char " ' " in front of the cell value.

Could you check this DSS in your environment?   If you turn off the feature, do you still experience issues?

Can you provide screenshots showing the error?