What do you mean, not beautiful is like a dragon entering the snake palace, although it is helpful to your family?

It means that a person's behavior or way of doing things is not beautiful enough, but it can help him build a beautiful family. "Like a dragon entering the snake palace" is a metaphor for a dragon entering the snake farm. Because dragons are bigger than snakes, they are out of place and not beautiful enough. But this metaphor means that although a person's behavior or way of doing things is not good enough, he may gain some advantages to help him build a beautiful family, such as gaining wealth and winning respect.