What does the term " Java EE stack " means in simpler terms with an example
It just means Java EE technology stack, ie. all the JSRs that are part of a java EE release and whose implementation will be provided by all Java EE certified application servers. (you won't need to provide yourself the libraries in your application).
Here for example is the Java EE 6 stack:
http://www.oracle.com/technetwork/java/javaee/tech/index.html