Unexpected error, need help

I were editing on my website then suddenly I think I made a mistake. I were editing on my front page, specefic something called functions.php. I haven’t deleted anything that already stood in the code-box, I simply wanted to add a ‘Author box’ or ‘About-me’ box.

And now I can’t enter my website in order to make changes at all.

Anyone know what I’ve done wrong?

I’ve attached a photo of how what it says when I try to enter my website