"的" is pronounced as "de" in Mandarin Chinese.

The character "的" is a particle used in Chinese grammar to indicate a possessive relationship, such as "John的书" (John's book). The pronunciation "de" is derived from the pronunciation of a similar particle in Middle Chinese, which was pronounced as "dək" and eventually became "de" in Modern Standard Mandarin.

Example sentences in Engpsh:

The book belongs to John. (John的书)
This is my pen. (这是我的笔)

Note: The pronunciation of "的" may vary in different Chinese dialects, so the pronunciation "de" is specific to Standard Mandarin.