Protecting a workbook is different from protecting the Excel file with a password to prevent reading/writing or locking the spreadsheet elements to prevent editing. Workbook protection forbids other users to add, move, rename or delete worksheets and defends against viewing hidden worksheets or hiding worksheets.
To protect your spreadsheet, Excel proposes the following options:
You can usually view formulas in an Excel cell when the cell is selected, but you can protect a spreadsheet by hiding the formulas in some cells.
Sometimes you might want to lock cells in your Excel spreadsheet that contain formulas and functions or data. Thus, the person doing the data entry will not accidentally overwrite or delete the spreadsheet formulas and functions or your data.