The official language of Vietnam is Vietnamese. Like Thai and Mandarin, Vietnamese is a tonal language that uses a change in pitch to inflict different meanings, and this can make it difficult for Westerners to master. While it is very different from Western languages, a traveler may be surprised to learn that the basic grammar is pretty simple. Verbs are static regardless of the past or future and parts of speech are pretty straightforward. The major difficulties lay on tones and certain sounds.
Vietnamese consists of 4 main dialects: the northern dialect spoken around Hanoi, the north-central dialect spoken around Vinh, the central dialect spoken around Hue, and the southern dialect spoken around Ho Chi Minh City.
While the Hanoi dialect is taken as the 'standard' and widely used in broadcasting, there is no de facto standard in the education system. Northerners naturally think that southern accent is for 'hai lua' (countrymen) and will always recommend you to be stick to the northern accent, but the choice of accents should depend on where you plan to live. If you are working in Saigon, the main economic centre of Vietnam, the southern accent is what you will hear every day.
For learners, the written latin alphabet is a relief. Unlike English, Vietnamese phonetics are accurate at reflecting true pronunciations, although their sounds on certain alphabets are different or even don't exist in English.
Vietnamese lexicons are heavily influenced by the Chinese languages. Some words are loanwords from China like hotel (khach San), children, communist party (dang cong san), some are formed based on Chinese characters (roots), like representative (dai dien) or bird flu (cum ga). The knowledge on the Chinese language will make it much easier to learn Vietnamese. Vietnamese is also full of loanwords from French and English from more recent times.
Although the Vietnamese people do appreciate any effort to learn their language, most seldom experience foreign accents. Learners may find it frustrating that no one can understand what they try to say. Staff in hotel and kids tend to have a more tolerant ear to foreign accents and it is not unheard of for a kid to effectively help translate your 'Vietnamese' into authentic Vietnamese for adults.
Besides Vietnamese, Ho Chi Minh City is home to a sizeable ethnic Chinese community, many of whom speak Cantonese. The more remote parts of the country are also home to many ethnic minorities who speak various languages belonging to the Mon-Khmer, Tai-Kadai and Austronesian language families.
English and French
As English is the most popular foreign language taught in Vietnamese schools, many young people have a basic grasp of English but proficiency is generally poor. However, most hotel and airline staff will know enough English to communicate. Directional signs are generally bilingual in both Vietnamese and English.
Despite Indochina's colonial history in which French was the medium of education, French is basically a non-functional language in Vietnam and aside from a few educated elite among the elderly, is much less useful than English when trying to communicate with locals. In the big cities, some of the big international luxury hotel chains will have staff who are able to speak other foreign languages such as Mandarin, Japanese, Korean or French.