Google made updates to the security measures related to app access, so you will not be able to use password. You need to use App Passwords.

In your Google account: Go to Manage your Google Account and select Security:

1. Turn on 2-Step Verification.
2. Once the 2-Step Verification turned on, the app passwords option will be enabled and it will be shown under 2-step verification.
3. Click on App passwords and create an App password and copy the 16 digits password which you got.
4. Use that 16 digits instead of the password in the Odoo email configuration settings

You can refer to google help for more details about how to create app passwords