You need to use Excel Application scope then Read Range to open each excel file.
The output of read range is a Datatable.
That will be the input in the for each row.
Within the first For Each loop create an Excel Application scope.
Within the Excel application scope - add a Read Range activity. (Fill in the correct values for sheet name).In the properties pane - Output assign the Output to a databale variable.
Now after the Read Range activity add the For Each row loop activity.
ForEach row in DataTable varaible mentioned above.
Check the For each activity if the type is String. if not try changing it to stiring. and make sure that GetFiles points to the folder containing your excel files.