This seems a strange sentence to have in the section on food :)
German is a different language so don't expect to learn the translation for English words and then speak it fluently. Don't give up and don't slack; you will be surprised by how much you missed. Find the reason you are learning the language and stick with it. https://www.youtube.com/watch?v=dNA3YSRGXoI
The difference is the person. English uses "are" for all singular you, we, plural you and they. In German, the forms are different for both yous (which are different words as well, du and ihr), we and they. They use du bist, wir sind, ihr seid, and sie sind ("we" and "they" do use the same form!).
Unfortunately, this is German & not your opinion.
Good = Gut; Nice = schön
They are similar but different words, as they are in English. When learning to translate, translate instead of changing the sentence meaning.
For example, the books are good could be referring to the physical condition in which the sentence could mean 'the books are okay, they're good enough' whereas 'nice' would imply the books are in mint condition.