What's the general thing? Is it earth? Timeframe?
I'd guess that there are powers? Is this a classic "good vs. evil" or maybe a "chosen one" hero coming into their own?
I ask more for curiosity than as a "am I gonna watch this" criteria. But no spoilers please!
~Jeordam
This is not Earth. It is definitely a different planet. What follows is all stuff the first few moments of the show will tell you, so these aren't spoilers, just world background:
The basic "magic" system is called bending. People can "bend" one of the 4 elements: Earth, Fire, Air or Water. People have divided themselves into 4 nations/polities based on this: the Earth Kingdom, the Fire Nation, two Water tribes in the North and South Pole, and the Air Nomads.
Only one entity, named the Avatar, can bend all 4 elements. And the Avatar (as the name implies) is constantly reborn, into each of the 4 elemental political entities, in a cycle. The Avatar's job is to maintain balance, between the 4 elements, the 4 nations, and the material and spiritual planes.
So in a way there is a chosen one. But there are chosen ones every few generations. And the show is definitely open to more than classical good vs evil. Redemption and destiny and growth are major themes, none of which sit well with clear cut good and evil.