You can't rename field labels at present, but you can add custom fields - more information here.

The Custom Page Layouts enhancement was suggested via our Ideas Forum and will be available in the next few months.  This feature will provide the ability to remove/hide the 'County/State' field and replace with a new custom field called 'Area'.

I'd recommend using the 'County/State' field within Workbooks, but just refer to and treat it as the 'Area' field in terms of your company's procedures and way of working.

Thank you!

You're very welcome.

I've also added a new idea to our Ideas Forum - Rename standard field labels and allow translation to multiple languages - to address the point you raised about being able to rename a field label.

Please feel free to take a moment to read and vote for the idea.  You can also add any comments regarding your specific requirement as this will help us define the feature's functionality.