Form NA5 is also called Application Form For Visa Issuance, Stay Extension for temporary residence of foreigners in Vietnam.
Form NA5 is required for Foreigners in Vietnam to extend or renew their visa.
Link to download : Form NA5 for visa extension
Vietnamese Visa application form (Form NA1) will be submitted at Visa landing counter desk at Vietnam airports to get the Visa into your passport. This form is required for all people who want to get Visa on arrival.
The Application for entry and exit Visa form is an important document that you have to submit to the Vietnam Immigration Officer when entering Vietnam. Since March 1, 2015, the old entry and exit form has been replaced by a new one which was renamed into Vietnamese visa application form.