1. Open the screen in Epicor where the field you are interested in resides.
2. Go to the dropdown menu Help -> Field Help.
3. This will open a flyout pane on the left.  Pin the pane to the left side so it does not auto-hide.
4. Click onto the field you want information on on the screen
5. Click on the Technical Details section of the field help
6. The information you are looking for is the entry in the DB Field section to tell you what the table and field name is that is behind the on-screen field.  If you cannot see the whole name, you can drag the separator to the right to make the field help bigger.