From the Abbot - March 2022 by Rev. Anwol Devadipa

Our Sunday morning Practice begins with 108 Bows. Bowing is a way to purify oneself. Before bowing I prepare the proper mindset. Through bowing I learn to humble myself and how to have a healthy body and mind. I bow to realize that other lives are just as valuable as mine. I bow to get rid of my selfishness. I bow because it is the desire of my true self. I bow for all living things, and for peace in the universe. 

Lotus Heart Zen's book 108 Bows of Great Repentance is a great resource. 

What started me on this topic was not the bows but the number 108. For the life of me I could not remember why this number is important. It was 3:00 am--so calling my teacher was not a good idea. Ven. Myohye would give me 108 reasons why it was a bad idea. But I could not get it off my mind. So, I'm now at my desk at 3:30 am, trying to sort some mail, I see this face, on the cover of a book, with this impish grin smiling at me. Now I can answer the question regarding why we have 108.
 
We have six doors of perception: sight, sound, smell, touch, taste, and thought. 
There are three aspects of time: past, present, and future.
There are two conditions of the heart-mind pure or impure, and
There are three possible attitudes: like, dislike, and indifference.

Korean Buddhists use this formula: 6 x 3 x 2 x 3 = 108 bows to cut through Karma.

Thank you, Ven. Wonji Dharma for providing the answer in his book It's All Good!