There is a big difference between knowing and understanding something. Knowing something only gets you to the start of a possible long journey. A long journey that must be taken to reach complete understanding.
When you are a child in the passenger seat you gain knowledge of how to drive. You know how to turn the wheel, accelerate and break. Pretty simple stuff. Then you go get your learners permit. You know the rules of the road. You “know” how to drive. But there is a big gap between where you are now and actually being able to drive properly. You will get in the car with one of your parents supervising. You will put the theory into practise. You will begin the process of understanding. Only after some time will you really understand what it is to drive.
Probably the hardest thing about this is that it is difficult to know yourself if you have reached the point of understanding or if there is a long way to go. For it is easy to think you have understood if you compare yourself to how you used to think previously. But you have no conception of what it is like to think at a more advanced level until you have actually reached it. This is why many people often assume they have advanced quite far down the road when in reality they have barely even begun. This is why we sometimes need a teacher who is further ahead to show us the way.
You may know a lot of great things. But the point where knowing transitions into understanding is the point where it becomes part of you, it becomes fully entrenched in your thoughts, words and actions. It is automatic.
This is why you can hear great words from someone who may genuinely mean them. But there is a gap between what they say and what they do. If you fully and genuinely understand something then you actions will always conform to it.