It emphasizes surprise. Some examples:
- Ты не ешь хлеб? You don't eat bread? / Don't you eat bread?
- Как, ты не ешь хлеб? What, you don't eat bread? (I can't explain, but "как" instead of "что" sounds better to me.)
- Ты что, не ешь хлеб? What, you don't eat bread?
- Ты не ешь хлеб, что ли? You don't eat bread, do you?
I learn Italian as well as Russian, and I find it very useful to memorise the notable similarities between the languages. It helps me learn more quickly, I think. E.G. Italian "biblioteca" translates to the Russian "библиотека". I imagine a similar strategy could be used between Spanish and Russian.
Finally came across this again, and I'll think of some examples. A big one that stands out is Russian "что" vs. Italian "che". They are slightly different words, but are used in a much more similar way than anything in English.
Also the word genders and verb declensions. I specifically only began understanding these in Russian when I compared to Italian (e.g. -ите = -ate; -у/ю = -o/io; -ть = re; etc.).
It's difficult trying to think of examples from the top of my head, but it's certainly true that I am frequently accessing both my English and Italian vocabulary during Russian lessons. In many cases the Italian word is closer to the Russian one than the English is.
Написал "Do not you eat bread?", в итоге ошибка и исправил на "Don't you eat bread?". Бред какой-то...