With the same gestures, there are many different meanings across different cultures, different countries.
It is common in Vietnam that people usually make the V-sign with their fingers (by extending the index and middle fingers with the palm facing out) when they pose for their photos (and even selfie).
Winston Churchill popularised the V for victory sign during World War II. V-for-Victory is also used by many people in the world, not just people in USA.
However, in Vietnam, it has nothing to do with Victory. In fact, not many people regard V as Victory. Even in cases that they know the meaning of the V-sign, they do not do it with such meaning.
The truth is that this signal just means the number two.
But, in Vietnamese language, number two is spelled “Hai”. It is the same “Hi” which means hello in English. So when Vietnamese people hold up the V-sign when they take photos, they mean “hello”. It’s a friendly, welcome gesture.
The thing is many people know that there are differences but don’t know exactly how it is different. So when you’re confused, just ask for an answer, don’t be shy!