There's no such thing as an ssh get command. You probably wanted scp, or maybe sftp.
ssh is the "Secure SHell". It's for securely connecting to a command shell on remote machines (think of it like secure telnet), or sending shell commands to be executed by another machine. ssh itself is not for copying files. ssh has a companion program scp (Secure CoPy) for securely retrieving files from another machine. The syntax for scp goes like this:
scp -r user@host:/path/to/folderName .
(The -r is for "recursive", which means it gets the target folder and its entire contents, not just the target folder itself.)
So what happened before?
The command you were running, well, either you had a config file set up to define the remote host to connect to, and possibly the user name to connect as, or you left out part of the command. It would canonically be written like this:
ssh user@host get folderName
Which means you were opening a secure shell on the remote host, and issuing the get shell command over there, with argument folderName. I don't have a get command on my system, but some brief Googling reveals that some ancient source code control systems such as SCCS and RCS may have had a get command, which fits with the error message you saw. I think you were accidentally invoking the SCCS or RCS get command on the remote system, but since the folderName wasn't a recognized source code repository format, it failed.
