The 12 jurors in the film are initially all convinced that the defendant is guilty, but as they begin to discuss the case, they start to realize that there are some inconsistencies in the evidence. They also learn more about the defendant's background and come to understand why he might have acted the way he did. Through this process, the jurors come to see the defendant in a different light, and they eventually vote to acquit him.
The moral of the film is that it is important to be willing to change one's mind when presented with new evidence, and to be open to the possibility that others may have a different perspective on things. It is also important to listen to all sides of a story before making a judgment, and to be aware of one's own biases. By following these principles, we can make better decisions and avoid making mistakes.