(.rar) files need to be open with WinRar or 7zip. Those programs can be downloaded for free and they help reducing the size of the download. Once you get one of those 2 programs you will be able to extract (.rar) files. I hope it helps!
Winrar : https://www.win-rar.com/start.html?&L=0
7zip: https://www.7-zip.org/
If it's still confusing I suggesting looking into what .rar files are on Google.com or tutorials on how to extract files or work with .rar files on YouTube.