Display something different than the real value of a cell

I want to display something different than the real value of a cell.

I have the following scenario:
There is a column which some rows of that colum will be editable and others won’t. So for those that won’t be editable I don’t want to display the real value of the cell. What I need to display is something different, for example “N/A” (that was just an example). That doesn’t mean that the cell value is “N/A”. It could be “30” but the users see that.

Any thoughts?

Thank you