What does it mean that Duke Zhou dreamed of teaching Grandpa to cook first?

Dreaming of ancestors talking to themselves, they will be famous all over the world; Dreaming of eating with the dead means a long life. Dreaming of holding S people in your arms, or shouting the name of the deceased, means dying. Businessmen dream that the resurrection of ancestors means making a fortune, and everything will be fine when talking to dead ancestors. Students dream of what their deceased ancestors said to them.