In a lot of languages nouns can be put together to form new nouns or more specific nouns. For example. There is a house and a garden. Or you put these two together and you have a garden house – a small house in the garden.
In German it is der Garten and das Haus and if you put them together they really become one word:
das Gartenhaus (the article always come from the last word – well, it is still das Haus, which is in a garden)
Putting together two nouns in German is nothing, though. We can have really long words, and I mean reeeeeaaaaaaaalllllllyyyyyyyy long!
To prove that, I will show you a funny video in a minute but will give you some words beforehand:
der Rhabarber = the rhubarb
der Kuchen = the cake
die Bar = the bar
der Barbar = the barbaria
die Barbaren (Plural)
der Bart = the beard
die Bärte (Plural)
der Barbier = the barber
das Bier = the beer
Now, here is the video: