It's about ninjas. That should be all you need to know.
Naruto himself is about 12 at the start of the anime. The basic premise is that the ninja village of Konoha was attacked by a giant, nine-tailed fox. The fox was defeated by the leader of the village, who sealed it inside a newborn baby, who just happens to be Naruto. The leader himself has to sacrifice himself in the process. So Naruto grows up with everyone shunning him because when they look at him, they think of the fox (which killed a bunch of people when it attacked). Because of this, he's constantly trying to prove himself. And he usually manages it, on account of two things:
1) He's incredibly stubborn, to the point of being beaten up, stabbed, smashed through rocks etc. then still getting back up, and
2) When he's getting his ass kicked the fox tends to give him a hand in the form of a whole lot of chakra (energy basically).
The story takes a few episodes to get momentum before it gets going, and the filler episodes in between episodes vary a lot in quality. I'm really not a big fan of the comedy present in anime, so while some of the filler eps are midly amusing, others get a bit annoying. But the whole point of Naruto is the ninja battles, which simply kick ass. I think that if you liked Hellsing you'll probably enjoy Naruto once you get up to episode 10 or so. That's roughly where I got hooked. :P
