Much like the classifiers described in Percepied's post, some spoken languages have words that label certain kinds of data. They assign items into certain classes used for discussion of such objects in general or for counting of objects.
One such example in English would be counting "sheets" of paper. This expression classifies paper into a sheet class. (Much like children objects in programming-ish terms)
The Thai language uses classification to a much greater extent than English. Not that English doesn't have classes for things but we tend to use short specifics like "5 ashtrays" and assume what sort of objects ashtrays are rather than say "5 ashtrays belonging to a meta-object that defines ashtrays, toilet seats, and intangible objects such as words". Thai has classes for everything from people (คน, "kon") to vehicles (คัน, "kun") to round & hollow objects (ใบ, "bai"). These are always used when counting (e.g.: "students 5 people" would be the typical grammar structure) and often used when discussing the class or sub-objects in general.
I'm sure many other languages use such classification systems.
Gritchka says: Strongly characteristic of East Asian languages: in Chinese, Japanese, and Indonesian the classifier is obligatory. As far as I'm aware all number + noun pairs have classifiers of the 'sheet', 'pipe', 'person' kind in those three, and of course many other regional ones.