When you protect the sheet, you can set different conditions to different areas of sheet, e.g. allow for some columns users to edit data, to add new data, etc, (I think the you can set all this from rightmost tab of format menu), and for some columns (e.g. columns with formulas) to restrict editing at all. Also you can there prevent users from seeing formulas in sheet or in certain ranges on sheet- the formula bar will display the value instead of formula.

Also from VBA Project you can set sheets with sensitive info, you don't want to share, to be "Very Hidden". Such sheets aren't displayed when user right-clicks on sheet tab and selects the option to hide/unhide sheets - they can be made visible from VBA project only! And when you protect the VBA Project itself with password, unless the user is an experienced hacker, the access to such sheets is effectively blocked. Put your sensitive info on table in Very Hidden sheet, restrict seeing formulas on any sheet for user, and users don't even have a clue that such sheet exists or how it is named!