As you've been told a rar file is a compressed file which is normally extracted via a utility, not always available on your system.
http://en.wikipedia.org/wiki/RAR#Extracting_RAR_files
A common one I use is
unrar which you'd invoke on a Linux command line as:
Code:
unrar x <rar-file-name>
If it asks you for a password, then the person who created the archive made it using a password and you'll need to find out that password to be able to extract the files. Otherwise it should just extract the files for you. Further, you can view the files in the archive to see what they are by typing:
Code:
unrar l <rar-file-name>
To see if you have unrar installed, type:
And further you can type:
To see more information about the command.