@Dinesh Prajapati Hello and welcome to Microsoft Q&A.
I understand you are trying to copy from excel to Postgres, but the excel has fewer columns than the postgres table, and this mismatch is causing copy to fail.
To get around this, use the Additional columns feature to generate extra columns to hold the place of the missing columns. You will then need to add these to the mapping, so we know which placeholder goes with which table column.
If this solves your problem, please mark as accepted answer. If not, let me know your blocker.