Google Authenticator is an application provided by the tech-giant which helps you in the quest of generating two-step verification codes on your Android machine. You might ask yourself what a 2-step verification system is. Well, in order to obtain stronger security for your Google Account, this protective system adds an additional layer of security on top of the standard one that uses a password.
As soon as the 2-step verification system is enabled for your account at Google and in other places, you are required to provide the correct password and the code generated by this application to obtain access to your specific accounts. You might not be asked for the 2-step code each time you're logging in inside your accounts, but if this thing happens, the app is here to generate a code for you.
The interface offers a straightforward layout which guies you through this entire process and you shouldn't run into problems. Accounts can be added here by scanning bar codes, or by providing a key. After this step is completed, you can check the list containing your accounts and their 2-step codes generated by the app itself. If you don't appreciate the standard blue and white theme, you can switch to a darker design each time you see fit.