The verb "ordnen" means to organize or to arrange but how does the addition of the preposition "aus" change the meaning? z.B. Er ordnet Wörtern aus Symbolen des Alphabets A Wörter über dem Alphabet B zu.
"Zuordnen" and "ordnen" are different verbs! And franlky speaking it's not quite clear what you're asking about.– EllerMar 27, 2018 at 14:38
"Aus" does not change the meaning of the verb here. It adds information: where does the protagonist take the things from that he is going to (re-)arrange. - Er ordnet Schrauben Muttern zu. --> Er ordnet Schrauben aus dem grünen Kasten Muttern aus dem roten Kasten zu. The aus dem x parts tell us where the person takes the hardware from.– Christian GeiselmannMar 27, 2018 at 14:44
The verb is "zuordnen": "Er ordnet X (dat.) Y (acc.) zu" means "He assigns Y to X". Here X is "Wörter aus Symbolen des Alphabets A", i.e., "words constructed from symbols of the alphabet A", and similarly Y is "Wörter über dem Alphabet B", i.e., "words over the alphabet B". Putting everything together, you get "he assigns words over the alphabet B to words constructed from symbols of the alphabet A", or equivalently "he assigns to each word over the alphabet A a word over the alphabet B".
Your verb is not ordnen but zuordnen (to assign).
Er ordnet ... zu.
"aus" is related to the alphabet symbols. He assigns words from (this is "aus") symbols... by the way this phrase sounds strange so I can't get what the part with symbols is supposed to mean.
You are misinterpreting where the aus belongs!
The general sentence is:
Er ordnet Wörtern Wörter zu
The verb here is zuordnen - a separable verb, which is why it says Er ordnet ... zu
All the other stuff is just there to closer define the kind of words that are being assigned. There are two kinds of words here
Wörter aus Symbolen des Alphabets A
Wörter über dem Alphabet B
So together it says
Er ordnet [Wörtern aus Symbolen des Alphabets A] [Wörter über dem Alphabet B] zu.
I'm using the square brackets here to make clearer what belongs together. There is no ordnen aus here.