SSHFS is filesystem based on the SSH File Transfer Protocol (SFTP). If you have server with enabled SSH protocol it’s 99% that this server supports SFTP out of the box. It comes very handy when you are working with remote servers and want to use favorite text editor and environment to work with remote files.
Some of the use cases are:
Example: if you want to use rsync but your server doesn’t have rsync installed you can always mount preferred remote directory via sshfs and sync it with rsync just like between local directories.