Highlight the data file and then click "Import" to map the data directly to the spreadsheet under the table information, recreating the XML table within your Excel spreadsheet.

Excel pro tips: Importing and parsing data When data dumps into your spreadsheet and it's a big mess, you'll know what to do.

To convert the other way (Excel to Google Earth), the easiest method is to use Google Earth Pro’s import feature described here. Another more complicated technique can be found here.