How does an Arabic speaking person sell a thing to an English speaking guy (the Arabic guy doesn't know English at all)?

This is an example of communication failure, unless they can use sign language. 

If The seller  has product, one can show that product , can make some sketches of it regarding the benefits , can use body language and signs. Booklets , leaflets , picture message can be used.

Personally , I will invest that much of  time searching for potential customer of my own language.

اhe can use selling materials :

1- videos -same customer language

2- catalogs

3- brochures

4- fliers

but it will not be an efficient way to market or sell a product. because the salesman cant give any further information or handle any objections, or detailed an unclear points 

Maybe, he can use body language.

Thank you for your invitation. I support colleagues answer & looking forward to new answer.

Thank you for the invitation.

I agree with Mr. Abdul Rahman

find yourself translator, or bring friend who can speak both language..