Kha (ख) (खवर्ण khavarna) is the second consonant of the Devanagari abugida.
In all languages, ख is pronounced as [kʰə] or [kʰ] when appropriate.
In this example, ख implements its inherent vowel, the schwa.
In this example, ख deletes the inherent schwa for correct pronunciation.
It is then transliterated as a x. Aryabhata used Devanagari letters for numbers, very similar to that of the Greeks, even after the invention of Indian numerals.