Prompt Title: Chinese Pronunciation Systems.

Certainly, I'd be happy to provide an example to help illustrate the meaning of the sentence in the context of Vietnamese:

In Vietnamese, the word for "to study" is "học" (學). This word was borrowed from Chinese and is pronounced "xué" in Mandarin. However, in Vietnamese, it is pronounced with the Sino-Xenic reading of "học," which reflects the historical pronunciation of the Chinese character in Middle Chinese. The Sino-Xenic reading system allowed Vietnamese to borrow Chinese words and integrate them into their language while preserving the original meaning and pronunciation of the characters.

Overall, the sentence you provided explains that the Sino-Xenic pronunciations are regular systems for reading Chinese characters in Japan, Korea, and Vietnam. These systems originated in medieval times and allowed for large-scale borrowings of Chinese words into these languages while preserving the original meaning and pronunciation of the characters. It is important to note that these languages are not genetically related to Chinese, excluding Sinitic topolects.