It means you can exchange one dinar for a little more than three US dollars.
Kuwait is a small country located in the Arabian peninsula. It's estimated that the oil reserves in this country make up around 9% of total oil reserves in the world, which to a certain extent explains why the value of Kuwait's currency is so high.
It should come as no surprise that the country relies on oil exports to the global market as its main source of revenue (95%). The biggest trading partners of Kuwait are Japan, Korea, India, and the United States.
Kuwait also comes in at 7th position on the world GDP per capita ranking list.