I have always heard that "eight characters are light". What kind of birthday is light?

Eight characters refer to "date of birth", and "eight characters are light" refers to "eight characters are weak"

No matter whether the eight characters are weak or strong

This person's life will have ups and downs.

"eight-character stability", a person's fate will be smooth sailing, ups and downs! Daoyou, do you understand? This box is so embarrassing!