The main everyday language in Qarshi is Uzbek, a Turkic language--albeit one heavily influenced by Persian, Arabic, and Russian. But other languages are spoken in other cities--Tashkent, the city of the ruling elite, is a much more heavily Russian speaking city, a legacy of it's role as the capital of the region under the Russian Empire and Soviet Union. I have met ethnic Uzbeks whose first language is Russian. The ancient Silk Road cities of Samarkand and Bukhara are actually Tajik speaking, though their own special dialects are quite unlike anything in the country of Tajikistan. Tajik is an Indo-European language closely related to the Persian of Iran and the Dari of Afghanistan. And lastly, in the northwestern autonomous region of Karakalpakstan, Karakalpak is spoken--another Turkic language, but more closely related to Kazakh and Kyrgyz than Uzbek.
The Uzbek so'm is the currency of Uzbekistan--although for larger transactions, it's also possible to use dollars (which are much stronger and better at retaining value than the so'm). The so'm has suffered from bad inflation since the collapse of the Soviet Union, and the current exchange rate is 11,800 so'm for 1 dollar.
