The Microsoft Fonts are needed in a Linux system when, for example a teacher asks you for a paper written in Arial and/or when you're using a Windows app through Wine. If you want to install them on your Fedora Linux system, the easiest way to go is searching for a pre-built rpm in RPMFind and then locating the one that suits your current fedora version to install it.
The always updated search link is this one:
So go and download the latest suitable RPM package from there and then install it with this command via the console:
sudo rpm -ivh path/to/msttcorefonts-rpm
And... That's it; The Microsoft fonts are now available/installed on your Fedora system.