Interface - Status Bar
On the bottom of the Bluefish window is the status bar. Shown here are messages, the current line & column number, the insert (INS) or overwrite (OVR) mode for the cursor, and the file type & character encoding.
The visibility of these items can be toggled via the View menu.
If you want to disable any of these items by default, you can set these options in the preferences under User interface.