In my business a cheque is made to an employee to purchase goods. The employee does not spend all the money only 490.00 out of 500.00. She provides receipts and the unspent 10.00. How do I enter this transaction in an excel sheet of simple income on one side and expenditures on the other side of the ledger

The entry should be allocated to both the expense and an account called cash. Suggest you get a low budget bookkeeping system like Quicken