This is the 2222nd most frequent German word.
elf
"Elf" in German means "eleven" in English.
Here, 'elf' is used as a cardinal number meaning 'eleven'.
Ich habe elf Äpfel gekauft.
I bought eleven apples.
In this sentence, 'Elfe' refers to a mythical creature called 'elf'; 'Elfe' is the nominative singular form in German.
Die Elfe lebt im Wald.
The elf lives in the forest.
Here, 'Elfen-', derived from 'Elf', is part of the compound noun 'Elfenbeinküste', meaning 'Ivory Coast'.