I went to a supermarket in this morninng.
I found bananas there, and I bought a banana them (or 'some').

I came home and I counted the banana them.
There ware 16 bananas a hand.
I was surprised, at it because usually there are 5 or 6 bananas a hand.

I said "bananas!!!" 

I cannot choose 'a banana', 'the banana' or 'bananas'.
It is very difficult for me.

From the wiki page on bananas;

"The banana fruits develop from the banana heart, in a large hanging cluster, made up of tiers (called hands), with up to 20 fruit to a tier. The hanging cluster is known as a bunch, comprising 3–20 tiers, or commercially as a "banana stem""

Which is where I got the term "hands" of bananas.