In Mongolia, the main language spoken is Mongolian! It is a very unique language that sounds nothing like Chinese or Russian, which are its border countries. The older generations in Mongolia often also speak Russian, since it was taught in schools while Mongolia was a satellite state of the Soviet Union. Many people from the younger generation can speak and understand English, since it is now the major language taught in schools here. There is also a subsection of Mongolians to the west that are ethnically Kazakh. There, they usually speak Kazakh at home and learn Mongolian later in school.
Mongolians use tugrugs (said like this: “too-groo-ks”). The current exchange rate is about 3,500 Mongolian tugrugs (abbreviated MNT) to 1 US dollar (abbreviated USD).
A bottle of water typically costs between 900 MNT (about $0.25 USD) to 2,500 MNT ($0.70 USD) depending on which store you go to and what size bottle you want to buy. The water is not too pricey, but my Mongolian teacher told me 30 years ago people used to just drink from the river that goes through the city, because it was so clean!