My value is in an avocado

Question

I watched a video

And now I feel like an idiot

They said a very large number

Was an avocado number

This many apples of origins

Would wait to be one lamb

They said twelve barb ins

Was twelve dimes of avocados value in

They said a hole of iron

would weigh more than 50 holes of hydrogen

Now dear reader

I, confused as you here,

Wish for you to tell me

The number described for thee

Hint:

Well you can guess by now that it's more or less horribly misspelled.

Answer 1

It's:

Avogadro's number, $6.022\times10^{23}$

I watched a video
And now I feel like an idiot

As best I can tell, this is just an intro with no other hints.

They said a very large number
Was an avocado number

The first misspelling of "Avogadro": avocado; it also happens to be a very large number.

This many apples of origins Would wait to be one lamb

As ffao points out, one mol of hydrogen ("this many atoms of hydrogen") would be one gram.

They said twelve barb ins Was twelve dimes of avocados value in

Carbon-12 is the basis for the unit of mols, so 12 mols of carbon (144 grams) has 12 times Avogadro's number of atoms.

They said a hole of iron would weigh more than 50 holes of hydrogen

Substitution of "hole" for "mole" makes this stanza true.

Now dear reader
I, confused as you here,
Wish for you to tell me
The number described for thee

As best I can tell, this is simply an outro with no other hints.