What's "a" is it an adjective?

Hi. Formally, it's an indefinite article (a man = any man). Compare to "the", which is a definite article: the man on the corner (no other man). Now, it can be considered a preposition only in informal speech when replacing "of": sorta sad (sort of sad) or a kinda mess (a kind of mess).

(By the way, I'm new to the Forum)

This has also been discussed recently in the thread Adjective or not?
It makes good reading.

I think our Guest merely meant to ask what "a." stands for when it's an abbreviation of something, to which I must answer that it depends on the context. Where did you find it?

"a" is an articile.

Is 'A' an adjective?

Is 'a' or 'an' used as adjective.