Russian citizens holding passport that is valid for at least 6 months or more beyond the date of arrival, are in the Vietnam visa exemption list with a visa-free length of staying of less than 15 days in Vietnam and single entry or exit.  According to the Immigration regulations of Vietnamese, if a Russian citizen

Yes… The Russian citizens can extend their visa. You should apply to extend before your current visa expires.

Vietnam is one of the most beautiful countries in South Asia that attracts travellers to its bustling cities, lush mountains, and golden sand beaches. Many people visit Vietnam for business purpose too.

All Russian citizens can enter Vietnam without a visa for a maximum of 15 days for both tourism and business purpose.  To get a free visa, you can just show your passport and enter Vietnam.