Samsung GT-S7392 is locked because of attempting password too many times. Please help me out Samsung GT-S7392 is locked because of successive password attempts; and I could not access or log into the google account as well. The question is: Can I l get unlock through theses using my google account where I'm not the first user of the device. It also asks me for the back up pin. What actually is it and how do I solve 'unlock' this? Please help me.
On a side note: This is very suspicious.
Anyway, regarding this question:

The question is: Can I l get unlock through theses using my google account where I'm not the first user of the device.

You can only unlock the device using one of the Google accounts associated with the phone. If you don't know the password or any of the phone's account credentials, then you're out of luck.
For the next question:

It also asks me for the back up pin. What actually is it and how do I solve 'unlock' this?

There is no universal backup PIN. You can only unlock the phone with the  PIN/password that was set or the credentials of an associated Google account.
Alternatively, you wipe the /data directory on the device to perform a factory reset, which will also reset the password.
Warning: Performing a factory reset will delete all user data.