Eastern European

Russian:

Russian has expanded as the official and communicative language of Tsarist Russia throughout the vast expanse of Eastern Europe and North Asia. Large Russian-speaking minorities still live in many other countries that mostly used other languages and which gained independence after the collapse of the Soviet Union.
In many countries around the world, including the United States and Western Europe, those interested in Slavic languages usually choose Russian as the first of these languages to teach themselves.
Russian is the official language in Russia, Belarus, Kazakhstan and Kyrgyzstan, as well as in Transnistria and Gagauzia in Abkhazia and South Ossetia.
TRANSLATIONS TO AND FROM – Russian

Ukrainian:

Ukrainian is the official language of Ukraine, the second largest state in Europe. In the eastern and southern parts of Ukraine, however, it competes with Russian; there, Ukrainian is spoken mostly in rural areas. Russian is used more in Donbas and the Crimea (only a small part of the population of the Crimea considers Ukrainian to be the native language), although in the central and particularly the western part of the country Ukrainian is by far the most commonly used language.
TRANSLATIONS TO AND FROM – Ukrainian

Bulgarian:

Bulgarian is a South Slavic language that is written in Cyrillic. It is closest to Macedonian. In addition to Bulgaria, Bulgarian is also spoken in many other countries to which Bulgarians have emigrated in the past. The total number of speakers is estimated at 9 million.
TRANSLATIONS TO AND FROM – Bulgarian

Romanian and Moldovan:

is a Romance language spoken by around 25 million people. Besides Romania, it is also spoken in the Vojvodina region of Serbia. In Moldavia, for historical and political reasons Romanian is called Moldovan.
TRANSLATIONS TO AND FROM – Romanian

Hungarian:

Hungarian is a Finno-Ugric language spoken in Hungary, parts of Serbian Vojvodina, in southern Slovakia, in the south of the Ukrainian Zakarpattia Oblast, in the Austrian province of Burgenland, in the northwest of Romania and in parts of Croatia. Hungarian is spoken by a total of around 13.3 million people.
Hungarian is not very similar to any other language.
The ancestors of the contemporary Hungarians used to refer to themselves as those who speak (“magyar”).
This word has also entered certain other languages in various forms, including Czech. However, most European languages took the name from the word Ungri (Hungari in Latin).
TRANSLATIONS TO AND FROM – Hungarian