Hello @Kalpana P,
Welcome to Microsoft Q&A forum.
Like the warning message indicates, the .nupkg file is not displayed in the text editor because it is either binary or uses an unsupported text encoding.
Normally, it’s a file which is related to NuGet package, no need to directly open it, and cannot be directly opened. Is there any particular reason that you want to open it?
If you really want to open it, you may try to rename the file extension from .nupkg to .zip. It’s more like a .zip folder/file. It includes some other files and folders, you can then extract and open this .zip folder/file.
BTW, as it seems that you are using VS Code(different from VS) and VS Code is currently not supported in Microsoft Q&A forum, please kindly post VS Code related questions here: Stack Overflow - Visual Studio Code.
Have a great day.
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