To rename file, focus it in file panel and go to File(s) > Rename, click respective toolbar button or use file context menu.

In-line editor box will appear over name of file.

Enter a desired new name and press Enter or click outside of the box to confirm. To cancel renaming press Esc.

Note you cannot rename remote files with SFTP-2 and older.

If you want to rename set of remote files using operation mask, use Move to function.