Visa is NOT required for citizens of Finland to stay in Vietnam for less than 15 days. If you intend to stay in Vietnam for longer than 15 days, then you have to apply for a visa and may have 2 options: Visit Vietnam embassy in Finland (Helsinki) or apply for a visa on arrival to Vietnam from Finland online. Finnish citizens may apply for both tourist and business visa to Vietnam for the stay of 1 to 6 months from Finland. Please check this link for visa fee for Finnish citizens.

All the information for getting a visa from Vietnam embassy in Finland can be found here: http://www.vietnamembassy-finland.org/