What does "sealing the arrow" mean?

Not long after the baby was born, I found a yin-yang teacher to set the date of birth for the child, arranged the eight characters, named it, and measured the fate to see if the child was a prosperous parent or a good parent. Are you here to ask for a debt or to pay it? Even better, Yi Shi also has the function of seeing through supernatural forces through his eyes, so that he can see whether there is an arrow on the baby's forehead in another space. If he finds an arrow on the baby's forehead, he must seal it before the baby's full moon. If he doesn't seal the arrow, the child will kill his parents. If his parents are too cruel to kill him, the arrow is spiritual and he will kill himself or his descendants in turn in the future. This situation is so serious that I can't figure it out through gossip. People who know how to have children should also know that this life-threatening problem, which is most closely related to human beings, comes from the inherent threat and danger of the human soul. It is the best policy to plan ahead and solve the problem as soon as possible.