Assuming you would like to know how to sync your Google account:
Go to Settings, and under the “Personal” section, tap Accounts.
Tap the icon for the account you want to sync (this may say “Google” or show the Gmail icon), and make sure the switch next to “Sync” is turned on.
If you don’t see your account listed, tap Add account.
Choose the type of account you’d like to add.
Follow the on-screen instructions to enter the account information and set up your account.
If you're having trouble syncing your account, you can try the following:
Open the Settings app on your device
Under the "Personal" section, tap Accounts
Tap the Menu icon
Tap Sync now
You can also check if everything is syncing properly by going to Settings > Accounts > Google > your @gmail.com address. If you see a message that says "Sync is currently experiencing problems," tap it for more information.