Okay kiddo, so a long time ago in the 1950s, there was a country called Vietnam. But some people in Vietnam wanted it to be divided into two separate parts. One part would be in the north, and the other part would be in the south.
There were a bunch of reasons why people wanted this to happen. Some people in the north believed in communism (which is when the government controls everything), while people in the south wanted a more democratic government (where people have more say in how things are run).
So after a lot of talking and arguing, leaders from different countries got together and decided to split Vietnam in two. The north became communist, and the south became democratic.
But not everyone was happy about this. Some people in the south didn't like the idea of being split off from the north, and they started fighting against the communist government in the north.
This led to a long, complicated war that lasted for many years. Eventually, the communist government in the north won, and Vietnam became a united country again. But it took a long and difficult journey to get there.
So that's the story of how Vietnam was split into two parts, and how it eventually became one country again. It was a complicated process that had a big impact on the people who lived there, and it's an important part of Vietnam's history.