No Turning Back' is an idiom that is used to express the idea that a decision has been made and there is no going back. It is often used to refer to a point of no return, where a person has committed to a course of action and cannot turn back. It can also be used to refer to a situation where a person has reached a point in their life where they cannot go back to their previous state. The phrase is often used to emphasize the importance of making a decision and sticking with it.