So, with 1-A, you can obviously have levels. There's baseline 1-A, and then 1 level above baseline, then 2 levels, then 3 levels, then 4 levels, and so on and so forth. And you can also have infinite levels of this. This infinity of levels can correspond to any imaginable infinity; you can have an aleph-1 amount of levels of 1-A, an aleph-2 amount, an aleph-65 amount, an inaccessible cardinal's worth of levels, and so it goes on, forever.
High 1-A surpasses any amount of these levels. For convenience, we call this a "meta"-qualitative superiority. (Though I don't like the name)
And then, with High 1-A, you can re-do the same process that you did back at 1-A. You can have baseline High 1-A, and then 1 level above baseline, then 2 levels, then 3 levels, then 4 levels, and then you can have infinite levels of this; you can have an aleph-1 amount of levels of 1-A, an aleph-2 amount, an aleph-65 amount, an inaccessible cardinal's worth of levels, and so it goes on, forever. Again.
But High 1-A goes further than 1-A, since you can also have a meta-meta-qualitative superiority. That is, something beyond any and all levels of meta-qualitative superiority. And you can re-do the same process described above with this one. And you can also have a level beyond any and all extensions of that, a meta-meta-meta-qualitative superiority. And so it goes on forever.
Of course, you can also have yet another hierarchy, except that now, each layer of it corresponds to another addition of "meta-" to the "qualitative" bit. So, Layer 1 is 1-A, Layer 2 is meta-qualitative, Layer 3 is meta-meta-qualitative, Layer 4 is meta-meta-meta-qualitative, Layer 5 is meta-meta-meta-meta-qualitative, and so on and so forth. And the totality of this hierarchy can have an amount of levels corresponding to any infinity, too. It can have aleph-0 levels, or aleph-2 levels, or aleph-10 levels, or κ levels where κ is a strongly inaccessible cardinal, etc etc.
And then you can really just have the entire hierarchy above be a single level in a larger hierarchy, and have this new hierarchy repeat the process again. You can repeat that forever. Extend it however long you like.
High 1-A+ encompasses all these possible extensions.