Hello. You didn't talk about which myth the question is referring to, which makes it impossible for your question to be answered.
However, most of the myths we know in our culture use the symbology linked to the numbers 3, 7 and 9, so I can help you by showing what each one means.
The number 3 represents the harmony and unity between all the elements of a body, or a system. This number is related to the power that we can emit with the complete and well executed union of our body, mind and spirit. In a myth, this number may be related to the deadline of a task that must be accomplished and that will make a character go through a great spiritual and physical growth.
The number 7 symbolizes perfection and can also be related to the meaning of the totality of the universe and bridge between two worlds, alluding to the rainbow and its seven colors. In a myth, this number can be related to many things, such as magic objects that allow a character to overcome a danger.
The number 9 symbolizes the end of a cycle, where an individual manages to reach his goals, complete his achievements and usurp his greatest dreams and wishes. One myth, this number can be related to the character's victory and the beginning of a new journey.
