I want to know what is an article used for in English as well as other languages. I have heard that some language have no articles and I'm wondering how do they work? As far as I know, an article is used to clarify the noun used with, as in number or volume, but I don't know whether I'm correct or not.
In English, articles are used primarily for explaining definiteness. The articles are, by the way, a/an, the, and sometimes some. (Arguably no article, the null article ∅, too.)
This refers to whether or not the speaker expects that the listener will know what the referent's identity is. For example:
I ate a cake.
In this sentence, I don't think you know which cake I ate.
I ate the cake.
In this sentence, I think you do know which cake I ate. You might not, but I think you do, whether it's because we've mentioned it earlier, or because it should be common knowledge.
I ate some cake.
In this sentence, I ate cake, but an unspecified quantity of it. This sentence doesn't assume that you know, or don't know which or what cake I ate.
I ate cake.
In this sentence, there's no article (or a null article ∅), which has a similar meaning to some cake.
If you speak of "the man" the person spoken to knows of what man you speak. If you speak of "a man" the person spoken to does not know what man you speak of and is waiting for further information.
The definite article the + man has the same meaning as: man (you know what man I mean). The indefinite article a + man has the same meaning as: man (you don't know yet whom I mean and I'm going to give you further information about this man).
Yes, there are languages without articles, eg Latin had no articles whereas Old Greek had articles. Astonishingly communication works even without articles, simply from context. In special cases Latin made use of a special adjective meaning a certain one to stress indefiniteness.
The function of the article has nothing to do with number or volume of a noun (what is volume of a noun?). The number is expressed by plural endings if the noun is in plural. "The" does not express number, whereas "an/a" always means singular.