If you’re not already in Ukraine, I guess the first thing you should know about Ukraine is this: Ukraine is a bilingual country. Almost all Ukrainians speak Ukrainian and Russian. Of course, most have a dominant language, a mother-tounge (one they speak at home etc.) but almost all can switch between the two.
Now, language is a sensitive subject here, but unless you like nationalist arguments, and unless you’re a Russian who thinks Ukraine is Russia – this wont affect you.
As a foreigner, you just need to know that two languages exist and this coexistence can be a little confusing. For example, the English name for the capital city is Kiev and this comes from the Russian spelling Киев. However, in Ukrainian, the city is Київ and, in English this would be Kyiv.
The official state language is Ukrainian, but state policy doesn’t change much. Many of my friends have websites such as Facebook which say that they live in Kiev and study at uni in Kyiv. They also bounce between the two languages and English when I’m around and many can also speak German, French and Spanish, Italian etc… Ukraine is a multilingual place.
Personally, I use Kyiv if I’m in Ukraine and Kiev if I’m outside of Ukraine, but it’s not a big deal. If Odessa (Russian) becomes Odesa (Ukrainian) you haven’t arrived in a parallel universe – your just in Ukraine. Expect to be confused.