What does it mean to break through the three levels in life?

The first level: birth; It is also a legendary life pass. There have been times when this checkpoint can't be crossed. The second level: marriage. The third level: 73, 84. That is to say, in Shandong, "seventy-three, eighty-four, the ghost king goes regardless of nature." (This is really verified. My grandfather died in 1984. )