Uses of さあ、まあ and なんか

Question

I understand meaning and uses of あの、えと。 But I get confused when people use さあ、まあ and なんか frequently while talking.

Answer 1

If I get your question right,

さあ Can mean :

• Who knows / I don't know
• Ok now/ there we go

And perhaps a few more, depending on the intonation.
Example:

Aさん:この人は誰？Bさん：さあね～。
Mr. A : Who is that? Mr. B : Who knows.

まあ Can mean :

• Now now(mother reassuring kid)
• Sort of, kinda.
• oh, my!(Usually used by baasan)

And perhaps a few more, depending on the intonation.
Example:

Aさん:うまくいった？Bさん：まあね～。
Mr. A : Did it go well? Mr. B : Kinda.

As for naka, perhaps you meant nanka. It is hard to explain, but can be used to mean things like you know or sort of.
Example:

Aさん:どうしたの？Bさん：なんかさ～、今朝から具合が悪いんだよ。
Mr. A : What's wrong? Mr. B : You know, I kinda don't feel good since this morning.