People in the Czech Republic primarily speak Czech, a Slavic language that is only spoken in this country. (Other Slavic languages are spoken in much of eastern and southeastern Europe as well as parts of central Europe and northern Asia.) Many people in Prague speak English, and I am currently taking an introduction to Czech course, so I can communicate with most people here. Besides English and Czech, many people here speak Slovak, German and Polish because the Czech Republic borders Slovakia, Germany and Poland.
Czech people use a currency called the "koruna," or crown. Their version of the dollar sign looks like this: Kč. There are about 20 Kč in a dollar, so $5 is roughly 100 Kč. Because the Czech Republic is part of the European Union, it will have to switch currencies to the euro (the standard European currency), but there is no clear timeline. Fun fact: an old Czech currency used silver coins called “thaler,” and although the spelling and pronunciation are slightly different, this is where our word “dollar” comes from!