how to exit administrator / text mode

I literally have no idea what happened and what the next steps are.
I installed the update to 18.04.1 LTS after restarting the computer. I found myself in admin (?) / Text (? – I do not even know the correct name).

He asks me to log in.
Apparently I enter the correct data.
That shows:

XXX @ XXX: ~ $

What should I write? Friendly request for 6-year-old level response, my understanding of coding is probably not at that level.

CTRL + D, exit, ~ Desktop – it did not work. Return to login and password request.

Any help would be appreciated.