Disk password

After I updated my MacBook Air to MacOS Catalina, I haven’t been able to get it started - it simply doesn’t proceed beyond the loading page with the Apple icon.

So I decided to reinstall the operation system and got it booted in the recovery mode.

Then, another problem has arisen - it requires something called “disk password,” of which I literally have no idea at all. :-( I did not install Mac OS by myself - it had already been installed when the MacBook was delivered to me.

Is there any way I can fix the problem? I feel my Mac has been “bricked”

Thank you for taking the time to read this, and I’d be even more grateful if you could help.