Why doesn't my iPhone 4 have Google Play? How can I get it?

I just got a iPhone 4 today and it doesn't have Google Play. Why don't I have it? How can I get it? It's iOS 6.1.3.

Google Play is only for Android phones; it wouldn't be useful on an iPhone because the apps aren't compatible with iOS. With an iPhone, the only place to get apps, music, games, etc. Is via App Store and iTunes.