If you forget the password required for setting up the email, there is no way to check the set password as a plain text string from cPanel.
If you forget your password, please try resetting your password.
STEP 1: Log in to cPanel.
STEP 2: Open an email account.
STEP 3: Open management.
Press the button labeled "Manage" to the right of the email address you want to reset your password.
STEP 4: Set a new password.
Enter the new password where it says "New password".
STEP 5: Save settings.
Press the button labeled "Update Email Settings" at the bottom of the screen to save your changes.