When we think about action we often think about swashbuckling pirates and fight scenes. Those are indeed action but in fiction we use action for more than just the fight scene. Action is an effective tool to tell a story.
1- Action is used to create the arc of a story. A narrative consists of action, reaction, change.
Jack is bit by a spider. Jack becomes a spider. Jack chooses to be a super hero.
2- Action is the way an author can convey to the reader information without telling it."I'm tired." OR "My arms and legs are sore and stiff, and feel like they're going to fall off. I can't hold my head up or keep my eyelids open."
3- Action is also used to develop a character.
Jack is an angry person. OR Jack slammed on his breaks and yelled out the window honking his horn, "Out of the way you stupid dog."
So liven' up your plot and characters with action! Be sure to check out all the other bloggers participating in the A-Z challenge here.