It refers to the blessings given by adults to their children, expressing their wishes for the child's health and bright future. Ningduo means "safety, stability, health", while Xin means "fragrance, good reputation". Ning Xiner is often used in written language.
Extended information
You can first find the explanation of the word "Ningxin" in "Cymology". It says this: In Jin and Song Dynasties, the meaning of "such" is the common saying. Wang Ruoxu's "Collection of Hunan Yi Lao·Miscellaneous Comments on Fallacies" quoted Chengyang layman's "Sangyu Miscellaneous Records": "Ning means likeness; Xin means language to help." Liu Yuxi's poem "Gift to the Japanese Monk's Wisdom Collection": "In order to inquire about Chinese studies Taoists, how many people win Ning Xin!"
Ning Xin'er's allusion comes from "Book of Jin": "Wang Yan, whose courtesy name is Yifu, has a clear and beautiful spirit, and a detailed and elegant appearance. Tao sighed for a long time, and then he looked away and said: "What kind of old woman can give birth to Ning Xin'er! But it may not be this person who misleads the people in the world." That is to say, Wang Yan is still a child (generally speaking, he is a minor). ), I once visited Shantao, one of the Seven Sages of the Bamboo Forest. After Tao waited for the child to leave, he commented: "What kind of old woman is she who gave birth to this child? Maybe he will be the one who misleads the people of the world in the future."?
Reference: Baidu Encyclopedia - Ning Xiner