if you protect the sheet, hidden rows and columns cannot be unhidden. If the sheet has data entry cells, you first need to format each of these cells to be Unlocked. That is a tick box on the Protection tab of the Format dialog. Untick the "Locked" tick box for each cell that people should be able to edit.
Then use the Protect Sheet command on the Review ribbon. You can add a password so that the sheet can only be unprotected with the correct password.
Be aware, though, that this protection is just to prevent inadvertent changes, not malicious intent. This password can be broken if a person puts sufficient energy into the attempt.
Best Response confirmed by
mdobbin99 (New Contributor)