"estoy aqui porque" -- (I am) here because
"me ha enviado" he/she/it has sent me -- note that the object, "me", comes before the verb, not after it. "ha" == "he/she/it has".
él tells us what exactly the subject is -- of "he/she/it" it's he.
I feel as though they should have left out object pronouns with this subject. I think it would be easier to add another subject with object pronouns rather than combining the two. I've never been so confused on where to put the me te lo le la los las se nos in a sentence.