Can someone explain what a 'Target Server' is in this instance. Also, what it means to "Target Multiple Servers"?
A Target server allows the job to be run against a different server than the one it is defined on.
Multiple Target Servers allows you to define a job once (say a routine backup job) and have it execute against many servers (thus backing each of them up).
MSDN Documentation here: http://msdn.microsoft.com/en-us/library/ms180992.aspx