Rar files are an archival file format that is similar to a ZIP file.? It is used to compress files and has the ability to support error recovery and file spanning.
.Rar files are used especially when broken into pieces to create one overall file, but in your case, it seems you only have one file which we can open up with a couple different options.
There are a few options to use when trying to open a .rar file.
Sometimes files are sent with parts such as r00 or r01 which are sequences of files that the computer will unpack to create one or a few files.? This is a huge advantage that .rar files have over .zip files except .zip are now innately supported on all operating systems.
As for the safety of the file, you should always be sure that file is sent from a trusted friend and then scanned over with an anti-virus software if you are still skeptical.? Some malware today can hijack the use of someones PC and use their email to push out bad files to friends and family from the address book.