Ilona is a feminine given name used primarily in Hungary and Finland, as well as in other parts of Central and Eastern Europe. The name Ilona is the Hungarian form of the Greek name Helenē (Ἑλένη), which is commonly interpreted to mean “torch,” “light,” or “shining one.” The name likely entered Hungarian through Slavic intermediaries such as Jelena. In Hungarian folklore, Ilona is also known as the name of the Queen of the Fairies, a mythical figure associated with beauty, magic, and enchantment. In Finland, Ilona is used independently of its Greek or Hungarian roots.
https://en.wikipedia.org/wiki/Ilona