Google Play is a digital-distribution multimedia-content service from Google which includes an online store for music, movies, books, and Android applications and games, as well as a cloud media player. The service is accessible from the web through play.google.com, the Play Store mobile App on most Android and Google TV devices. Purchased content is available across all of these platforms/devices. Google Play was introduced in March 2012 when Google rebranded it's whole digital distribution strategy and merged Android Market and Google Music services to Google Play.
With Google Play you can:
Store up songs (20.000 songs available)
Download apps on the Android Market (+450,000 Android apps and games)
Browse the world's largest selection of eBooks
Rent thousands of movies
Starting March 6th 2012, Android Market, Google Music and the Google eBookstore will become part of Google Play.
How to access to Google Play US version?
The solution is very easy, it consists of switching your IP into an US one. A Virtual Private Network is a software which is able to make you appear as an American by providing you a new IP.