What’s with this (English) obsession with counting nouns? For a better understanding, we can use the notion of DETERMINER (function word). This word called DETERMINER tells the listener/reader which noun are we talking about:
- one in GENERAL (“a” or “0” = nothing) or
- a SPECIFIC one (“the”).
In other words, the FUNCTION word preceding the CONTENT word tells us what information (about the noun) is available to the speaker/writer & listener/reader.