However, some users who rooted their Nexus 5 or installed custom ROMs found that they couldn't access Google services, including the Google Play Store. This was because Google services required a specific set of permissions and configurations that were not present in custom ROMs.
If you're running Android 5.1 on your device, you'll need a compatible version of Google Services APK. The version you need might depend on your device and region.
Go to Settings → Security → Unknown sources (enable). google services apk android 5.1
Includes Google Play Protect , which scans your device for malware and protects your data.
Enables leaderboards, achievements, and cloud saves through Google Play Games. Why You Might Need the APK Manually However, some users who rooted their Nexus 5
As time went on, Google continued to update its services and APK files, making it easier for users to access Google services on their Android devices. Today, Google services are an essential part of the Android experience, and most Android devices come with them pre-installed.
Google, being the developer of Android, had a suite of services that were essential for Android devices to function properly. These services included Google Play Services, Google Maps, Google Drive, and others. The version you need might depend on your device and region
You're looking for information on Google Services APK for Android 5.1.
Google uses a variant code in the filename: