To sign in, add your Gmail account
When you add an account to the Gmail app, you can sign in to the app using that account. You can also add multiple accounts to the app and switch among them.
If you aren't on the latest version of the Gmail app, update the Gmail app.
On your Android phone or tablet, open the Gmail app Gmail.
In the top left, tap Menu Menu.
To the right of your username, tap the Down arrow Down Arrow.
Tap Add account.
Choose the type of account you want to add.
Follow the steps on the screen to add your account.
After your account is added, you'll be signed in to Gmail any time you open the Gmail app.