What is the meaning of Kasra?

In Arabic script, the vowel point for "i", appearing as a small diagonal line placed below a letter ( ـِ ) and designating a short i /i/. If the Arabic letter ي (yāʔ) immediately follows, it indicates a long ī /iː/.

In Iranian Persian represents the vowel /e/. If the letter immediately follows it represents the diphthong /ej/. This usage differs from other Arabic script languages and from classical Persian, in which the diphthong /ej/ did not occur.