Hi Lilly the best thing is open the form to view the data and right click on any one of the fields then go to setup there you can see the Tablename.field name.
Or else open the form in AOT → Forms then expand the data sources node of the form, there you can see all the list of data sources select any one of the data sources right click and go to properties there you can see the table name.
Happy Daxing…