By Travelerguide 
An arrival permit may also be called an arrival visa, which does not have to be obtained beforehand at a consulate or an embassy of the given country but is issued upon the traveler’s arrival to the country at the airport or the border.
Can I apply for a Vietnam visa on arrival?
Yes you can, Vietnam does permit the visa-on-arrival program for residents of the UAE. However, applying online and receiving an approval letter is mandatory. They can get a visa from one of the international airports in Vietnam with the help of this approval letter. This is valid only for air travel and only for the standard types of visas like the tourist or business visa.
You Should Have Following Required Documents.
1. Your Passport (Original and Copy).
2. Emirates ID Copy.
3. Filled Application Visa Form.
4. Noc Letter from your Company.
5. Passport Size 2 Photographs.
6. Book Flight Tickets.
7. Reserved Hotel Voucher.
Get more information about Vietnam Visa.