How is Ukraine involved in Hunter Biden pardon?

Fibis I am just an average American. My teen years were in the late 70s and I participated in all that that decade offered. Started working young, too young. Then I joined the Army before I graduated High School. I spent 25 years in, mostly in Infantry units. Since then I've worked in information technology positions all at small family owned companies. At this rate I'll never be a tech millionaire. When I was young I rode horses as much as I could. I do believe I should have been a cowboy. I'm getting in the saddle again by taking riding lessons and see where it goes.