To get a clear description of a computing term look it up in Wikipedia.
Consider the expression "a computing term" in that advice. The intent is that advice applies to any piece of computing jargon you may be interested in: the advice is just as good whatever the actual term might be. The expression "term" functions as a formal parameter of the advice, while the actual term you look up, like "formal parameter" would be the actual parameter of a Wikipedia search.
Notice how the word "term" could have been replaced with many others ("word", "concept", "thing", "search term", "X", etc) The idea is the same whichever we choose - this is what is meant by saying it is a formal parameter. But the fact that the advice applies with special force to computing terms does matter. (Wikipedia is not always as useful) This is a common feature of formal parameters: we often find ourselves needing to limit the domain of advice to some particular type of thing.
In the body of the advice "it" is used to refer to the actual value of the parameter. In computing languages you are often more explicit: to get a clear description of a computing term, look up that term in Wikipedia.