Or when you open the VBE, is the Funcres file showing codes.
Or when you open the VBE, is the Funcres file showing codes.
Or may be it's just Option Explicit code line there.
If so then you can ignore that as it does not saved with XLSX, such a behavior can be disabled in VBE - Tools - Options - Editor - Require Variable Declaration, but it is useful for coding.
Is the code actually in the workbook that is automatically opened when you open Excel, or as JoeMo has suggested?
If the code is in the standard workbook that is opened with Excel, then perhaps you have a workbook with VBA code in your Excel 'Startup folder'. See Customize how Excel starts