That’s the best you got?
Truth is always the best defense. You can read what it says in clear and simple language.
It protects slavery. I believe Lincoln himself says in his first inaugural that Article IV, section 2 does in fact protect slavery. If you like, I'll go check and if I have remembered correctly, i'll give you Lincoln's words telling you the same thing that i'm telling you.
Perhaps Lincoln's words are the best i've got. I'd say for most people, the mere text is good enough to grasp the meaning.
"It is scarcely questioned that this provision was intended by those who made it for the reclaiming of what we call fugitive slaves; "
He says some more stuff you won't like on the other side of the above link.