Translation:The children found a new world in the wardrobe.
"Combining two words to make a new word is very common in Esperanto. The vowel ending of the first word may be dropped, and this is what people usually do, unless it makes the pronunciation too difficult.
The -o at the end of the first word may be retained if it makes the word easier to pronounce: tablo + tuko (table + cloth) = tablo-tuko, tablotuko (table cloth); Esperanto + klubo = Esperanto-klubo, Esperantoklubo.
The addition of the -o is optional, but it is recommended to avoid jaw-cracking consonant clusters. Also note that additional hyphens can be added optionally in the middle of a compound word to increase understanding, if desired."
Taken from the tips & notes.