Structure tool window and the Structure popup

To open the tool window: View | Tool Windows | Structure or Alt+7.

To open the popup: Navigate | File Structure or Ctrl+F12.

Available as a tool window or a popup, the Structure view shows the structure of the current file and lets you quickly navigate in that file.

For a table in the table editor, the Structure view shows the list of columns and lets you hide and show the columns, sort the data, and perform other, associated tasks. See Using the Structure view to sort data, and hide and show columns.