Beats
No, No, not the beet that you eat nor is it the beat that means I beat you. This beat means your describing what your characters are doing as they are talking to people in their dialog .
"That cat is crazy!" Yelled George as he clung to the branch of the tree.
Here is my advice on beats. Go in and add beats to all your dialog when you are first learning to do beats.
Then go in and take it away were it is too much or takes away from the story.
"That's stupid." Jan rolled her eyes as she sipped at her tea.
"I know, I know, but that's what he did." Said Cara as she added sugar to hers.
"What is he planning on doing with it when he's done making it?" Jan leaned back in her chair.
"Beats me, but he's spent hours working on it." Said Cara sipping her own tea.
Now take beats away
As you can see the beats have become too much here. So erase them in fact if you are having a conversation between just two people you can get rid of the he said, she said parts after your introduced them. So now read it after I've redone it.
"That's stupid." "That's stupid." Jan rolled her eyes as she sipped at her tea.
"I know, I know, but that's what he did." Said Cara as she added sugar to hers.
"What is he planning on doing with it when he's done making it?"
"Beats me, but he's spent hours working on it."
It's a simple edit but it reads much better.
Beats are important, they help build the scene, but be careful not to overdo them. It is better to add then take away than to not have enough in writing.
Here is a sight to help you practice but they're calling them dialog tags not beats.
http://www.readwritethink.org/files/resources/interactives/dialogue-tags/
Listen