How do you tell someone who has never seen Hetalia what its about?

Well here's how I describe it to other people: Hetalia is a Japanese anime about history. Basically all of the countries (well not all only about 40) are personified, so Italy, Germany, America ect. Are all characters who act out history together. The majority of the show is centered around the Axis Powers and Allied Forces of World War II but they also jump around to other historical events to such as The American Revolutionary War, The War of Austrian Succession ect. But I wouldn't watch it if you are easily offended because the entire show is entirely based off stereotypes, so that character's personality is based off of the stereotypes of the country they are. For example, France is a huge romantic, Germany is really strict, America is stuffing himself with hamburgers.
The show might be kind of confusing at first because it doesn't really have much of a plot line. At times it might seem kind of random. But once you get into it, you'll see it's one of the most funniest and educational animes there is.

Hope this helped :)

I have to explain all the time so here's what i say:

Hetalia is a japanese animation based on WW2.
Each country is represented with a character and they reenact world history in a funny and interesting way.
:D

The other explanations are way better than anything I could say so I guess i can just sum it up in one word...
AWESOME