的 marks possession in Chinese, and it is simple to use.
Structure
Noun 1 的 Noun 2
Noun 2 belongs to Noun 1.
我 的 书。My book.
Expressing close possession
的 can be omitted, particularly when talking about personal relationships such as family and close friends.
Example
我 妈妈。
My mom.
我 妈妈 的 朋友。
My mom’s friend.我 妈妈 的 书。
My mom's book.