The spelling of the word "Jilleisa" can be explained using IPA phonetic transcription. The first syllable, "Jil," is pronounced as /dʒɪl/, with the soft "g" sound. The second syllable, "lei," is pronounced as /leɪ/, with a long "a" sound. The final syllable, "sa," is pronounced as /sɑː/, with an open "a" sound. Therefore, the correct spelling of the word is "Jilleisa," with a soft "g" in the first syllable and a long "a" sound in the second syllable.