If Type – Talk

The article states that the if type is a "helper type". I need a stricter definition of both the "if type" and the concept of "helper type" in general. To help you understand what I'm asking, look at the following:

if ( expression )

As you can see, that is an incomplete if statement. Is the term "if type" meant to refer to the part of an if statement consisting of the reserved word if followed by a boolean expression enclosed in parentheses, as exemplified above? If not, clarify in good, unambiguous english.