Red Hat is an operating system. It has been out since 1995 or 1996 and went through a few iterations before it became a true enterprise solution. Basically, they changed their name and changed the version name back between about 2003 to 2005 when they came to that point.
Satellite is a package management solution most commonly used to maintain patch levels and security updates. It is something like what SCCM (System Center Configuration Manager) does on Windows servers and Windows workstations.