"The loaf of bread is big; it is a big loaf of bread."
Translation:Das Brot ist groß; es ist ein großes Brot.
Your translation is correct, but I don't know anyone that says "ein Laib Brot". For everyday conversation "Brot" is fine.
The original sentence refers to a LOAF of bread, and a native German speaker would use Laib for loaf. By the way, you can buy ein halber Laib Brot.
Marlen, I agree with you entirely. I know a lot of Germans who use Laib for loaf, it is acceptable.
I think "eine Scheibe Brot " should be considered correct, but I'm not mothertongue, so I'm not 100% sure
venturiano - eine Scheibe Brot is simply a slice of bread! Viele Grüße aus Berlin.