Step to see Internal column name:
1.Open list.(whatever your list is) <br>
2.Click on gear icon located on top right side.
3.Click on **List Settings**
4.Then scroll down, you will find column names in left side of screen.
5.Click on column name.
6.Then see its URL
i am attaching screenshot for your reference.[![enter image description here][1]][1]


[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/SPVPx.png
  [2]: https://i.sstatic.net/cGkvs.png