Google Play Services

Hi everyone, i just ask what the benefits if i use Google play services ?
and thanks answer me

 

If you add into your game leaderboard / achievements. That's what game services is all about (Game Center)

 

Thanks for answer, i do all steps to add it but it say when testing game ( sign in error) do you now solution please, i searched too much but no solution

 

It says Testing Game, because you did not complete all steps. You have to add Linked Apps too in order to publish Game Services.