Google has officially released the Android Pay app into the Google Play Store, meaning that as long as you have a compatible device, you should be able to go to the Play Store and download it onto your Android phone. For current users who have the Google Wallet app, downloading Android Pay will effectively replace that app.
However this should not be confused with the other Google Wallet. For those unfamiliar, instead of Google Wallet facilitating mobile payments, the app will now exist as a mean for users to transfer money to each other, whilst Android Pay will act as a service in which users can pay for their purchases at counters using their smartphones.
Either way with the release of Apple Pay, Android Pay, and Samsung Pay, it looks like the mobile payments scene is hitting up and it will be interesting to see who will be able to come up on top.