Can I specify arguments for a Meth...

What is an EL Function?

The Unified EL defines something called an EL Variable. This is a variable that is used in an expression to point to some other expression. It is typically used for loop control variables in tags such as JSTL's <c:forEach>:

<c:forEach var="item" items="#{inventory.allitems}">
   <h:outputText value="#{item.name}"/>
</c:forEach>

In the above example item is an EL Variable because under the covers, it actually refers to the expression: #{inventory.allitems[index]}

It is stored in the ELContext instead of living in some ordinary scope. See the Unified EL Spec and the VariableMapper class in the JSP 2.1 JavaDoc for more details on EL Variables.