Filies or Fillies: How To spell?
The word Filies is misspelled against Fillies, which is plural of "Filly"
Fillies has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings fi & ies which should not be misspelled with single 'L'
Wrong Spelling:  fi-l-ies  Correct Spelling:  fi-ll-ies 
Find more wrongly spelled words of Fillies to spell it well.