Bruce Willis. You may know him from movies like “Die Hard,” “Look Who’s Talking,” “Pulp Fiction,” or even as Elizabeth’s dad on the series “Friends.” The actor has a long list of credits to his name and multiple projects that are currently in post-production. That means we will see the actor on the big screen yet again, but he will not be taking on any new acting roles.

Demi Moore, Willis’s ex-wife and mother to three of his children, broke the news on Instagram that Willis has a cognitive condition called aphasia, and due to his battle with this condition, he has decided to stop acting.

Many of us had never heard of aphasia before learning that Willis has it. That raises many questions like what is it and why would it cause him to decide to stop acting?

In short, aphasia is a condition that impacts a person’s ability to communicate. The person with the condition will have trouble communicating and might also have trouble understanding what other people are saying. We completely get how it would be nearly impossible for someone to act if he or she can’t communicate clearly. Reading lines would be a potentially impossible task.

TODAY’s Hoda Kotb and Savannah Guthrie sat down with Dr. Gayatri Devi to learn more about what aphasia is including common causes, symptoms and cures. While Dr. Devi has not treated Willis, she is quite knowledgeable about aphasia since she is a professor of neurology at Hofstra University.

Watch the video below to learn more about what aphasia is and what it isn’t.

We find ourselves at a loss for words every once in awhile, and sometimes we struggle to think of the right word or name for what we’re trying to describe, so we’re pretty glad to learn that’s normal and not a reason to be concerned that we might have aphasia.

Willis’s family has not revealed details about how Willis got aphasia or what type he has, so we do not know if his condition could be improved upon with speech therapy or not. Hopefully he is doing well otherwise and keeping his spirits up.