An embassy is a piece of home territory in a foreign country, which is there to help compatriots in need or local citizens before they travel to the country it represents.

In Czech, you can either say velvyslanectvi or ambasada.  Like-wise, the word for ambassador is velvyslanec or you can simply say ambasador. 
    There are over 90 embassies or foreign consulates in this country, and the Czech Republic has over 360 embassies, general and honorary consulates and other diplomatic offices all over the world including 17 Czech Centres, which promote Czech culture, trade, and tourism.
   If you want to come to the Czech Republic and your country is not among those which have a visa-free regime or bezvizovystyk with the Czech Republic - which means there is a visa requirement - vizova povinnost between the two countries - you have to apply for a visa or vizum.  For that you need to come to a consular office or konzularni urad and fill in a form - tiskopis.  You also need a valid passport, which in Czech is shortened to pas, and one passport photo - that's pasova fotografie.  A regular tourist visa -  turisticke vizum - is issued for 90 days.  It  is either a single entry visa - jednorazove vizum - or a multiple entry visa or vicena-sobne vizum.  If you want to work or study in the Czech Republic, you have to apply for a special type of visa which is valid for more than those 90 days.
    After the fall of communism the Czech Republic introduced a visa-free regime with most of the developed countries of the world.  If you take part in Radio Prague's annual competition and win a trip to Prague, you might find some of these words useful wherever you come from.