The ZIP codes are only used for US addresses , and not for other countries which use Postal codes of various formats. Some countries like UAE don't use either as many here get their mail thru numbered P.O. Boxes. The term ZIP stands for Zone Information Program of the US Postal Service. It is not an international code.
So if you are required to enter the ZIP code by some online shopping website etc , you have 3 choices:
1 - If the order form allows it (i.e. drop down country list), change the country to UAE and it should automatically adjust the form without need for a ZIP to be entered. If it does not then probably the company does not ship international any way , so first check their shipping policy or FAQ page.
2 - Enter 00000 and see if it accepts that. ( you should not enter an actual valid ZIP used in US because their computer will just add a US location to your address messing up the address for you).
This should work on many vendors that actually ship outside US , but it will be useless if they don't.
However if they state they do ship outside US , verify UAE is on the list of countries they ship to. If so you can just enter any alphanumeric text in the ZIP field because in this case it will just be part of the printed address. For example your city name instead of 5 digit ZIP. Do not enter a P.O.Box in this field because private couriers cannot deliver to P.O. Boxes. Only orders thru USPS international service can arrive in P.O. Boxes in UAE (Empost). But this service is extremely slow.
3 - get a Shop & Ship account from Aramex (or many others you can google) , this account will provide you with domestic US (or Europe or Hong Kong) forwarding address you can have your orders sent to , and then you can go to the courier website and have them forward the item from their address to you . There is an additional cost per KG & fee for this service. But you can use it to order from US vendors that do not have international shipping themselves for whatever reason.
Alternatively , you can just try and find the product locally and save yourself all this headache. At least the locally purchased items come with a warranty and you are rest assured it is not damaged during shipping , and in some cases they send you the wrong item and you have to send it back.