There is no way to check a Gmail password on a mobile device. \nThe only way to check a Gmail password is to log into the account on a computer and view the password in the account settings.
Can I See My Passwords On My Phone?

No, you cannot see your passwords on your phone.
Can I see my passwords on my computer?? No, you cannot see your passwords on your computer.
How Can I See My Google Account Password?
There is no way to view your Google Account password.
Where Does Android Store Gmail Passwords?

Android stores Gmail passwords in the device’s memory.
The Gmail app for Android uses OAuth 2.0 to authenticate and authorize access to a user’s Gmail account. OAuth 2.0 is a standard protocol that allows users to grant third-party applications access to their online services without sharing their passwords.
When you add a Gmail account to your Android device, the system stores your account’s user name and password in the device’s memory.
How Do I Find My Email Password On My Samsung Phone?
There is no way to find your email password on your Samsung phone.
If you have forgotten your email password, you will need to reset it.
Where Are Passwords Stored On Samsung?
Passwords are stored on Samsung devices in the device’s memory.
How to view passwords on Samsung??To view passwords on Samsung devices, go to the device’s Settings menu and select the “Security” option. Then, select the “Passwords” option to view a list of all stored passwords.