How to understand and explain words “bare handful”?
You are one of the bare handful for whom there is no need to learn.
How to say that phrase in other words?
When you grab something (like grain) with your hand, the amount of grain you can hold is very limited and it is small. The word handful means:
A small number or amount: 'only a handful of people were in the pub.'
The adjective bare is used as an intensifier (attributive) to emphasize the small number in your context. For example:
All you need to get started with this program is a bare 10K bytes of memory
10K byte memory is an extremely small amount of memory and the adjective bare intensifies the meaning.
Your sentence could be rephrased to:
You are one of the extremely small number of people for whom there is no need to learn.
In other words:
There are so many people for whom there is need to learn, but you are an exception (there is no need to learn for you) that is not easy to find (in this world).
[Oxford Online Dictionary]
"Bare handful" in this case has the sense of "very few".
A "handful" in this usage is generally a small amount (imagine the amount you can hold in a single hand)...
Only a handful of people know the location of the secret base.
"Bare" means minimum or least possible.
She eats only the bare minimum to stay alive.
Combining the two gives you a "bare handful" - or an minimal handful. So, while a handful of people might be 20, a bare handful may be more like 5.
When used differently, note that "handful" can also mean "troublesome" or "difficult".
That kid sure is a handful.